wildlife fact file - primitive animals - pgs. 11-20
DESCRIPTION
Loligo Squid, Leech, Sponge, Giant Octopus, Northern Red Anenome, Armored Millipede, Brain Coral, Centipede, Sea Squirt, Common CuttlefishTRANSCRIPT
LOLIGO SQUID
PHYLUM Mollusca
ORDER Decabrachia
CARD 11
Attracted by the light of the moon shining on the sea, loligo squid gather by the thousands every March to mate and spawn in the shallow waters off Southern California.
KEY FACTS
SIZES Length: Head and body, 8 in. Tentacles: Eight arms, 2 in. Two long tentacles extend to 8 in. for
catching prey.
BREEDING Sexual maturity: 3 years. Mating season: March. No. of eggs: Laid in sacs of 200-300. Each female lays about
20 sacs at a time. Hatching: 3-4 weeks.
LIFESTYLE Habit: Usually solitary, although huge schools gather during mating season.
Range of the loligo squid.
DISTRIBUTION
Diet: Mainly fish. Lifespan: 3 years.
RELATED SPECIES
The loligo squid is found throughout the warmer waters off the west coast of North America, extending south from San Francisco to Mexico.
Closely related to the common squid, Loligo vulgaris. Giant squid of up to 60 ft. (including tentacles) are found in the northern Atlantic Ocean.
CONSERVATION
I Although the loligo squ id is fished extensively each year, the
I fish.ing .is controlled, and this species is not yet in danger of extinction.
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FEATURES OF THE LOLIGO SQUID
The arms and tentacles of all squid are covered with suckers to provide a powerful grip that is used when hunting. At the center of the tentacles is the SQUid's mouth that has a horny beak with which it tears up prey before swallovying it. It has two well-developed eyes. In some species, notably those that live at great depths, eyes are also light-producing organs.
Two long tentacles used fOT catching food .
Eight arms, sometimes called short
Suckers
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Eyes
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There are more than 300 species
of squid, ranging in size from less than half
an inch to over 60 feet in length. The loligo squid grows
to approximately eight inches and, like all its close
relatives, has eight short arms and two long tentacles
that it uses to catch prey.
~ FOOD &: HUNTING Squid eat fish and crustaceans primarily. The loligo catches a fish by grasping it in its long tentacles. It paralyzes its prey with venom produced by its salivary glands and bites off the prey's head.
The squid's torpedo-shaped body enables it to move rap-
idly over short distances. It changes color to blend in with its surroundings and so becomes invisible to both its prey and predators.
The squid's only defense is to escape behind the dark clouds of "ink" that it squirts into the water.
DID YOU KNOW? I ~ BREEDING • The giant squid, Architeu- I On moonlit nights in March, this, is the world's largest loligo squid gather near the living invertebrate. water's surface. The group • The giant squid's only consists of males and females predator is the male sperm that are ready to mate. whale. A live squid measuring The males find mating 40 feet long has been found partners as quick as possible inside a male sperm whale. since the presence of so many Female sperm whales eat other males creates competi-much smaller squid. tion for available females. As • Squid possess the largest a male becomes excited, his nerve fibers of any animal. head and tentacles become
• The most dangerous squid are found off the coast of Peru . They live in schools and hunt in the same manner as the piranha, tearing their victims to shreds in seconds. • In 1961 a gold medallion was found inside a loligo squid caught off San Sebastian, Spain. It had been lost by a swimmer in Barcelona two years earlier and 900 miles away.
flushed. He then seizes a female and retrieves a sac of sperm from his own body that he inserts into her body with one of his tentacles. The eggs are thus fertilized in the female's body and she then lays them in jelly-filled sacs, each containing 200 to 300 eggs.
Each female produces approximately 20 sacs that are joined together in flower-
shaped configurations and are as large as 1 0 feet across. The sacs are attached to each other with a sticky secretion that prevents them from being washed away.
Tiny squid hatch from the egg sacs three to four weeks later. They are moved and spread by coastal currents.
In three years they are fully grown and ready to mate.
Above: Loligo squid lay their eggs in large clumps.
Right: The eggs hatch several weeks later and the tiny squid break free from their jelly sacs.
left: Squid mate in groups.
~ SQUID&:MAN The breeding habits of the loligo squid make it particularly easy to catch.
Fishermen in California catch the majority of squid in March, when the squid gather to mate. The squid are attracted to light, so the fishermen hang lamps on their boats to encourage them to rise to the surface. Several thousand tons of squid are caught each year.
Still, because they produce so many eggs, the loligo squid are in no danger of becoming overfished. But fishing is controlled because, if the squid were hunted on a larger scale, it would endanger the other marine life that preys on the squid for food.
LEECH
PHYLUM Annelida
CLASS Clitella
GROUP 6: PRIMITIVE ANIMALS
ORDER Hirudinea
Most leeches are parasites, feeding on the blood of other animals. Some can ingest five times their body weight in blood at a single
feedin~enough to sustain them for up to a year.
KEY FACTS
SIZES Length: Up to 6 in .
BREEDING Sexual maturity: About 3 years.
Mating: Summer. No. of eggs: 5-15 in cocoon.
Hatching time: 4-10 weeks.
LIFESTYLE Habit: Mainly aquatic, although
some are amphibious or terrestrial. Diet: Generally parasitic on the
blood and body fluids of living
animals; some are predatory.
lifespan: Possibly up to 20 years .
RELATED SPECIES
There are some 650 species of leech worldwide. Their closest
relatives are earthworms, marine
lugworms, and ragworms.
Range of the medicinal leech.
DISTRIBUTION
Leeches occur worldwide. Medicinal leech restricted to
Europe and the Ural Mountains, and countries bordering the eastern Mediterranean.
CONSERVATION
The medicinal leech is endangered, due to vast numbers
collected in the last century and, more recently, the disap
pearance of suitable habitat. They are now protected.
FEATURES OF THE MEDICINAL lEECH
The bloodsucking medicinal leech lives in fresh water where cattle and horses-its main source of food-come to drink.
Body: Long and slightly flattened. Olive green , with reddish- brown stripes.
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Underside: Green or yellowishgreen.
Sucker: Used to hold leech in place while it·feedS.
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Leeches are generally disliked because
of their bloodsucking feeding habits.
Yet these relatives of the earthworm were
once highly valued by doctors, who believed
that using leeches to drain some of a patient's
blood cured all illness.
~ CHARACTERISTICS A leech is a flattened, segmented worm related to the earthworm. Its body is shaped like a compressed cylinder, with an intestine, nerve cord, and vein system running the length of its body. It has dense muscles that allow it to move like a
leech has a highly developed sucker. Bloodsucking leeches attach themselves to their prey with these suckers. When they are not feeding, they attach themselves firmly to rocks or vegetation.
Most leeches live in water because they need moist
snake or curl itself up in a ball conditions in which to survive, as a defense against attack. since they become dehy-
At each end of its body, the drated if they are exposed to
~ FOOD &: FEEDING Many species of leech are active predators that attack and eat other small invertebrate animals.
The fish leech has mouthparts similar in function to a hypodermic syringe and uses them to feed on large animals. The fish leech is a good swimmer; it will attach itself to a passing fish and puncture its skin to feed off its body fluids.
The most well-known leeches are those that suck the blood of land animals and birds. Some of these parasitic leeches live on land, but most are found in shallow or still water.
The medicinal leech feeds off the blood of cows, horses, and humans. It has three serrated, semicircular jaws that can slice a Y-shaped wound into the
skin of its prey. The jaws secrete a fluid that enlarges the animal's blood vessels and prevents the blood from clotting. The fluid also contains an anesthetic, which deadens any pain the animal may otherwise feel, and thus
Above: Leeches live in the stagnant waters of a pond or river to keep from dehydrating.
dry air for too long. Some species live in the ocean, but most live in stagnant pools and slow-flowing rivers.
Most of the species that live out of water are found in the moist, tropical rainforests, where they live among lowlying vegetation.
allows the leech to feed unnoticed. The leech can drink as much as five times its body weight in blood and take several months to digest it.
Below: The victim of the fish leech usually survives the attack, although it may be weakened.
DID YOU KNOW? • Thousands of medicinal leeches are bred for medical research each year at the world's first leech farm in England . • Following a leech bite, blood continues to flow from the wound for several hours .
The leech was once used to leeches had nearly wiped out suck the blood of ailing people the population. But with the in the mistaken belief that the advent of modern medicine, practice would remove the the use of the leech declined poisons along with the blood. and its numbers increased. Doctors applied the medicinal Live leeches are still used in leech to their patients. Due to modern microsurgery and are this practice, the doctors them- applied to patients to pro-selves were referred to as mote healthy blood flow in leeches. grafted skin tissue. They also
By the nineteenth century, secrete a chemical that can the demand for medicinal actually dissolve blood clots.
~BREEDING Every leech has both male and female sex organs. When they mate, one will act as the male and fertilize the other with its sperm. Some species place the sperm directly into the female's genital opening.
The fertilized eggs do not develop inside the leech's body but, rather, are ejected into the water and bathed in a nutrient fluid contained within a sac of mucus. The mucus eventually envelops both the leech and the eggs, forming a protective cocoon. Some species attach their cocoons to submerged objects or bury them in damp soil, and the young emerge four to ten weeks later.
Top right: This medicinal leech is sucking blood from a human hand.
Right: In some species, the eggs will develop inside a cocoon attached to the adult's body, and when the young hatch, the parent allows them to cling to its body.
• The giant Amazon leech grows to a length of 18 inches . • Leech collectors used to catch them by wading barefoot in the water and then picking them off their skin and transferring them to a jar.
SPONGE
PHYLUM Porifera
GROUP 6: PRIMITIVE ANIMALS ... CLASS ~ Oemospongiae
Sponges look like plants, grow like plants, and even reproduce themselves like plants, but they are not plants. They are one of the
most unusual animals on earth.
SIZES
Length: Up to 6 ft.
BREEDING
Sexual reproduction: All sponges
generate both eggs and sperm.
Sperm is released into the water in
summer to fertilize eggs, which
become mobile larvae.
Asexual reproduction: Seedlike
particles called gemmu/es are re
leased in fall, lie dormant through
winter, and develop into sponges
in spring. Fragments of adults may
also grow into new sponges. LIFESTYLE
Habit: Sedentary. Filter-feeders.
Diet: Suspended and dissolved
organic debris, bacteria.
RELATED SPECIES
There are some 5,000 species of
sponges worldwide that form the
subkingdom Parazoa.
Range of the sponge.
DISTRIBUTION
Found worldwide in all seas, from the lower shores to the
ocean depths. Some freshwater species are also found in
rivers, lakes, and ponds.
CONSERVATION
The bath sponges Spongia officina/is and Hippospongia equina are overcollected in places, but most species are in
no danger of extinction.
HOW THE SPONG E FEEDS
WATER IN The sponge draws water into central cavities through small pores and chambers. These cavities are lined with cells that digest food particles suspended in the water. Mobile cells called amoebocytes move 'through the sponge and carry nutrients to other cells.
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Flagellae: Whiplike tails lining the cell walls.
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tWATER OUT Water is driven out of the cells by the whiplike tails of the flagellae.
Osculum: The passage through which water is driven out.
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Sponges are found all over the world in lakes,
rivers, and seas. They live in rock pools along
the shoreline as well as in deep ocean trenches.
Some sponges stand alone, forming shapes that
resemble fingers or flasks. Others may fuse together
into shapeless masses that cover submerged rocks.
~ CHARACTERISTICS Sponges have many cells, but these cells can survive independently of one another, unlike the cells of higher animals. For this reason, sponges are sometimes regarded as colonies of single-celled animals that cooperate to obtain food.
A sponge is basically a mass of these cells arranged in a series of tubular or spherical groups, each with a central opening. The entire cell struc
Right: The skeletons of sponges are 75 times more absorbent than cloth.
ture is reinforced by an internal "skeleton" that is either pinned together with tiny barbs of silica or lime, or held together by a mesh of resilient protein fibers. The fibrous skeleton of the warm-water marine sponge is what is used as a natural bath sponge.
~BREEDING Each sponge has both female and male organs. In summer a sponge releases clouds of sperm. The sperm cells are drawn in by nearby sponges to fertilize their eggs. The tiny larvae settle on the seabed and grow into new sponges.
Sponges also reproduce asexually. If a sponge is split into two or more parts, it may regrow into separate sponges.
Left: The tubular form of some sponges provides an ideal hideout for small invertebrates.
Right: Under a microscope, it is possible to see living cells grouping together to form new sponges.
DID YOU KNOW? • Many sponges produce toxins that can poison sharks. Scientists are now studying ways to use these toxins as shark repellents. • Like geraniums, sponges can be cultivated by taking cuttings. This method is used
It may also grow a lobe of tissue that forms a new individual (called budding). In fall many sponges produce seedlike particles called gemmules. The parent sponge disintegrates, but the gemmules sprout into new sponges in spring.
Right: The silicon spikes of some freshwater sponges can cause allergic skin reactions.
to produce bath sponges. • Sponges contain compounds of medical interest, including some that have been used to treat arthritis. • Some sponges secrete acids that enable them to bore into coral reefs .
Most sponges have developed effective defense systems to deal with predators. Some species, such as the river sponge, contain thousands of tiny silica needles that make them hard to eat. Many tropical marine sponges contain chemicals
~FEEDING Sponges feed by drawing water in and then filtering out any suspended food particles. The group of cells works together to draw the water through minute pores in the structure into chambers that are lined with cells that can "swallow" the food particles. These cells have whiplike tails called f/agel/ae, which drive the water through the system and out through a large cen-
Left: A sponge growing among reef coral takes the shape of the coral's folds.
that are toxic to fish as well as other predators.
Because they are loose communities of cells, most sponges can survive being broken up into smaller fragments. Each piece simply reorganizes itself and grows into a tiny sponge.
tral opening. Once taken in, the food is passed to cells called amoebocytes. These cells move through the body of the sponge, carrying nutrients to other cells and releasing materials used to build the skeleton.
Some sponges have algae living in their bodies. These single-celled plants manufacture food by photosynthesis -using sunlight to convert chemicals into carbohydrates. The algae may pass some of these nutrients to the sponge.
GIANT OCTOPUS
ORDER Mollusca
FAMILY Cephalopoda Octopus dolfeini
For years the giant octopus was feared as a monster of the deep. But in reality it is a highly intelligent, resourceful animal
that is quite harmless to humans.
KEY FACTS
SIZES Tentacle span: Up to 30 ft. Weight: Up to 600 lb. Studies indicate a trend toward larger individuals in deeper water.
BREEDING Sexual maturity: About 1 year. Male matures at a smaller size than female. No. of eggs laid: Up to 100,000. Hatching time: 6 months.
LIFESTYLE Habit: Solitary. Lives on the seabed. Diet: Crabs, mollusks, and occasionally fish. Lifespan: Averages 3 years.
RELATED SPECIES The giant octopus is a distant rel
ative of garden snails and slugs. Closer relatives include other octopuses, squids, and cuttlefish.
Range of the giant octopus.
DISTRIBUTION
Found along the coasts of the northern Pacific, from California to Alaska and west to the Sea of Japan.
CONSERVATION
The giant octopus is vulnerable to pollution. But unlike its edible relative, the common octopus, it is not in direct danger from humans.
PECIAL ADAPTATIONS OF THE GIANT OCTOPUS SUcklrs: Suckers are used to rip prey apart and to anchor the octopus to a rock. Sensors surrounding each sucker allow it to reject anything that tastes or feels wrong.
Siphon: The siphon, or funnel ,
takes in water. The octopus can
use it to propel itself through
water.
T .... el.: The octopus has eight strong arms. They are capable of pushing and pulling and can grip prey very tightly.
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allk: The giant octopus uses its powerful beak to crush crab shells
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The giant octopus is a highly developed mollusk
that has very acute senses, excellent mobility,
and remarkable mental agility. It is so well adapted
to its marine environment that many zoologists
consider it the pinnacle of evolution
among invertebrates.
~ HABITS The giant octopus spends most of its day lurking in a rocky crevice. It emerges at night to forage for prey. The site of its hideout is frequent-ly marked by the shells and fragments of its victims--crabs, clams, cockles, and sea snails.
If it does venture out, the octopus usually crawls along the sea floor, often with surprising speed. Buoyed up by the water, it may walk on "tiptoe,"
pushing itself along with the tips of its powerful tentacles. Or it may glide along, propelled by a jet of water thrust out of its gill chamber. If it is alarmed, it can escape at high speed, jetting backward with tentacles streaming. Its soft body lets it squeeze through small openings.
Right: Suckers on its strong tentacles anchor the giant octopus to a rock surface.
DID YOU KNOW? • A giant octopus can live out of water for some time if it stays cool and damp. It may leave the water to search for food on land.
• The giant octopus has the largest brain of all the invertebrates. It has a very good
~ BREEDING The male octopus is easy to distinguish from the femaleone of his tentacles has no suckers near the end . He mates by inserting this tentacle into the female's mantle cavity. A sperm package is propelled down a tentacle groove into the female's oviduct, where the sperm fertilize her eggs. The male octopus dies soon
after mating. The female may produce up
to 100,000 eggs, which she strings up on the ceiling of her lair. She watches over the eggs for six months, never leaving the nursery or eating.
Each egg hatches into a tiny
Left: Messages from the brain to cells in the skin cause the octopus's color to change.
memory and can learn quite complex tasks.
• Although the octopus has three hearts, they are not very efficient. Because it has poor stamina, the octopus cannot sustain a struggle for a long period of time.
------'
octopus only a quarter of an inch long, which immediately swims off to join the plankton. It settles on the seabed and begins to grow at an amazing rate-from a weight of half an ounce to two pounds or more within seven months.
~ DEFENSES Enemies of the giant octopus include seals, sharks, and larger giant octopuses. Its main defense is its speed and its ability to squeeze into tiny cracks and crevices. It can also confuse an attacker by squirting it with a dense cloud of ink.
~ FOOD &: HUNTING The giant octopus eats almost anything it catches, but crabs and bivalve mollusks are its main prey. It hunts mainly by sight and has eyes that have a lot in common with ours.
The octopus surges forward and envelops prey with its tentacles. It checks the catch with its suckers, which have touch sensors and chemical receptors, and it will reject anything that feels or tastes
Above: The giant octopus lies outside its lair waiting for prey to enter its territory.
Meanwhile the mother has died, exhausted by the effort of breeding and starved by the six-month vigil she kept over her eggs.
Nerve-controlled color cells in the skin let the octopus change color for camouflage or an intimidating display. As a last resort it will bite. If these defenses fail and the octopus loses tentacles in an attack, it simply grows new ones.
wrong. Sometimes the octopus paralyzes its victim with a shot of venom from its salivary gland. But usually it rips prey apart with its powerful suckers. The octopus kills crabs with a shell-crushing bite from the parrotlike beak that is concealed at the center of its radiating tentacles. Then it scoops out the crab flesh and dumps the shells outside of its lair.
NORTHERN RED ANEMONE -----;-- - -- ----- -- ~- ~ - -- -- --- - -- - - --~--;---- ------.--- ..... <l' -----;--- ~----
... ORDER '11IIIIIIII Actiniaria
• r ......
FAMILY Actinidae
GENUS &: SPECIES Teatia fetina
The northern red anemone is a beautiful marine animal that spends most of its life below the tidemark around temperate
shores. It is one of the largest anemones in the North Atlantic.
CTS
SIZE Body: Diameter, up to 5 in.
BREEDING Asexual reproduction: Divides in
two, or small individuals bud off.
Sexual reproduction: Eggs and
sperm are released into the water
to produce tiny free-swimming
larvae.
LIFESTYLE
Habit: Solitary, but may occur in
groups from the tidemark down to
about 325 ft. Prefers to attach itself
to a rocky, shady spot. Diet: Small crustaceans and small
fish.
RELATED SPECIES
There are over 6,000 species of
anemone and coral. The genus
Teatia contains several species,
including several varieties of the
northern red anemone, T. fetina.
Range of the northern red anemone.
DISTRIBUTION
The northern red anemone is a temperate marine species
that occurs in the coastal waters of the North Atlantic and Baltic Sea.
CONSERVATION
Although not specifically threatened, the northern red
anemone is affected by pollution and habitat destruction, as are many inshore marine animals.
FEATURES OF THE NORTHERN RED ANEMONE The northern red anemone exists in a number of different varieties, which may be red, gray-blue, or green. Identification is also complicated by the existence of similar, closely related species.
Tentacles: Tapered and flexible . Over 100 arranged in rings around the central opening. Translucent (light can shine through them), and often red. Armed with poison cells that spring out in attack.
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Retracted form: Rubbery, jellylike appearance. The anemone generally reverts to this position at low tide to avoid drying out. It also retracts as a defense mechanism.
Protrusions: Sticky warts on
the surface of the body attract
grains of sand and gravel for
camouflage.
Base: A strong foot (hidden) attaches the anemone to a rocky spot from the mid-tidemark down to about 325 feet.
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The northern red anemone appears fairly static,
sitting on the seabed with only its brightly colored
tentacles waving gently in the current. But when a
shrimp or small fish brushes past, its /ightning-
fast stinging cells paralyze the animal. The
anemone can then use its tentacles to
draw the victim slowly into its mouth.
~ HABITS The northern red anemone oc-curs on the seabed, from the mid-tidemark down to about 325 feet. To avoid bright light, it attaches itself to a rocky surface in a crevice or seaweed.
The column of the northern red anemone is covered with sticky gray warts. Sand and gravel stick to the warts and camouflage the anemone.
When approached by a predator like a large fish, the anemone pulls in its tentacles so that only the squat, rubbery column shows. If attacked, it squirts out
Right: When exposed at low tide, the anemone retracts its tentacles to avoid drying out.
a jet of water and contracts its tentacles even more.
To avoid drying out at low ti.de when it may be exposed to air for several hours, the anemone retracts its tentacles and shrinks to a jellylike blob. It expands again when the tide covers it.
~ FOOD &: FEEDING The northern red anemone feeds on small invertebrates and fish. Attracted to the anemone by its colorful tentacles, the prey sees it as potential food or a place to take shelter.
As soon as the prey comes into contact with the anemone, groups of stinging cells resembling tiny barbed harpoons are fired from the tentacles into the victim. These cells are called
Left: The northern red anemone lives in fertile waters to depths of about 325 feet.
DID YOU KNOW? • The sting from a northern red anemone's tentacles can cause a rash on sensitive parts of the human body.
• Some anemones use their poisonous tentacles to stop other anemones and corals from settling close to them.
• A few anemone species give
nematocysts, and the tip of each is filled with a poison that para
lyzes the prey. Chemicals released by the vic
tim cause the anemone to contract its tentacles and open its mouth, drawing the prey into the central body cavity. Nutrients are absorbed, then waste material is passed out through the central opening, which serves as both mouth and anus.
Right: The brightly colored tentacles vary greatly in different anemones.
birth to live young that form within the parent's body.
• Specimens of the species Tealia columbiana may grow up to three feet across.
• The internal organs of the northern red anemone are arranged in a circle around a central axis.
The northern red anemone can reproduce sexually or asexually. It can release both eggs and sperm into the water where the egg is fertilized by the sperm, producing a larva (an imma-
Left: Underwater, its tentacles make the anemone look like a flower in bloom.
Left: The anemone is a simple animal known as a coelenterate. It has a sac/ike body with a central opening that is used as both a mouth and an anus.
ture form between egg and adult). The larva settles on a rocky site, where it then develops into a tiny anemone.
It can also produce tiny replica anemones by budding (producing offspring "buds"), or by dividing down the middle to form two individuals.
Left: A strong foot attaches the northern red anemone to a rocky surface. It changes its position with a deliberate creeping motion.
ARMORED MILLIPEDE - - - - - r ~ r- ~~ ,:trt ..,..
.... PHYLUM '1IIIIIIII Arthropoda
CLASS Dip/opoda
.... FAMILY '1IIIIIIII Various
•• _ ~ ~;..... ; i:l.~':. • _ ~ -...
Armored millipedes vary in size, with some species reaching almost a foot in length. Despite their shell-like armor, many rely on
poison glands to deter enemies from attacking.
~ . - -
SIZES Length: The largest millipedes can reach 1 foot in length. Other
species frequently grow to 8 in.
BREEDING Mating: Male and female may embrace for several hours. Fertilization takes place within the female's body. Eggs: Depending on species, may
lay up to 300 eggs.
LIFESTYLE Habit: Nocturnal. Range of armored millipedes.
DISTRIBUTION
Diet: Leaves and other decaying vegetable matter on forest floor. Some species forage in trees.
RELATED SPECIES
Found in the United States and in tropical forests around
the world.
There are 8,000 species of millipede worldwide.
CONSERVATION Armored millipedes are not directly threatened. But, like
other inhabitants of tropical forests, they are at risk from the continued destruction of their habitat.
SPECIAL ADAPTATIONS OF ARMORED MilLIPEDES
Defense: The millipede curls into a spiral, exposing only its hard armor plating to an enemy.
Color: Species may be brightly colored or striped to deter predators and indicate that the millipede .is inedible.
move in a ripple down the length of the millipede.
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Armored millipedes rest during the day.
At night they forage for rotting vegetation among
the dead leaves on the tropical forest floor.
The wavelike pulse of their short legs gives them
considerable power when burrowing.
~ HABITAT
Armored millipedes push their way through soil and decaying vegetation with ease. Under
piles of leaf mold or in damp crevices, millipedes can be
found resting by day or feed
ing at night. There are also some species that climb trees to feed on vegetable matter caught in the branches.
Above: A cluster of eyes at the base of each antenna can be seen on this giant millipede.
~ FOOD &: FEEDING Unlike centipedes, with which they are often confused, armored millipedes do not hunt
living creatures. Instead, they eat the leaves and other matter that fall from trees and de
cay on the ground in their tropical forest habitat.
Millipedes may also attack crops planted by humans. But they are unlikely to be a principal source of damage. Their jaws are simply not strong enough to pierce anything
that is not already damaged or decaying.
left: Decaying vegetation on the forest floor provides food and lodging for millipedes.
Right: The millipede's rippling motion can be viewed under a microscope. This way of moving developed many millions of years ago.
~DEFENSES Because armored millipedes move slowly, they are vulnerable to attack. As a result, they have developed several means of defense.
One defense is the armor
itself. Many species, such a.s the pill millipedes, curl up into a ball when attacked. Some species become as large as a golf ball. Another defense is poison glands. In most cases the poison is constantly secreted to give the millipede a toxic coating. Some larger species can spray their poison as far as three feet.
Other defenses include bright markings to warn off
predators. A millipede that lives in the sequoia forests of California is even luminous.
~ BREEDING
Armored millipedes may mate for several hours. The male winds around the female and holds her with his front legs. Fertilization occurs within the female's body. Depending on the species, she may lay up to
300 eggs. Unlike earthworms and most
insects, many female centipedes and millipedes tend their eggs. Some disguise the eggsbycoatingthemw~h
excrement. Others build an intricate nest and coil them-
DID YOU KNOW? • Millipedes first appeared about 400 million years ago.
• The name millipede means 1/1,000 legs. 1/ But millipedes
rarely have more than 200 or 300 legs.
selves around the eggs. Various kinds of nests are built. The usual materials are soil and excrement, although some millipedes spin a nest of a silklike substance.
When it hatches, the ar
mored millipede may have only a fraction of the adult number of legs. It gains more legs every time it molts, or sheds, its hard outer shell.
Below: After elaborate leg-waving courtship rituals, millipedes may mate for many hours.
• One species of millipede was oOnee ground up and
used to poison arrowtips.
• Some millipedes spit a fluid that can cause blindness in humans.
Scleractinia Dip/oria, Meandrina, etc.
A brain coral is not a single animal, but rather a colony of tiny creatures. These organisms sift through the water for food,
trapping and paralyzing their prey with miniature poison darts.
KEY FACTS
SIZE
Diameter of colony: Up to 61$ ft.
BREEDING
Sexual reproduction: Spawns in
late spring or early summer, a few
nights after full moon.
No. of eggs: Several thousand,
depending on size of colony.
Asexual reproduction: Colonies
grow by sprouting new but geneti
cally identical polyps.
LIFESTYLE
Habit: Fixed colonies grow on
skeletal limestone.
DISTRIBUTION Diet: Microscopic floating animals
supplemented by nutrients made
by single-celled plants that live
within the coral.
Brain corals are found on coral reefs in the Caribbean Sea,
Pacific Ocean, and Indian Ocean .
RELATED SPECIES CONSERVATION There are many different species of
brain coral belonging to two fami
lies. All corals are relatives of sea
anemones and jellyfish.
Like all reef species, brain corals are threatened by pollution,
coastal development, and, in the long term, global w arming.
Some corals are collected and dried as souvenirs for tourists.
FEATURES OF BRAIN CORALS
Form: Domelike or egg-shaped in appearance. Living polyps cover the surface, building upward and outward. Beneath them lie the skeletons of dead polyps.
Habitat: Warm , clear, shallow water with a firm bed . Most corals colonize rocky areas or submerged wrecks. Sunlight is an essential requirement.
Polyp (detail): Tiny organism that is the basic unit of the colony. Arranged in dense rows. Each polyp has a crown of tentacles with poison darts for killing its tiny zooplankton prey.
Mouth: Lies at the center of each polyp's tentacle crown . The prey is
passed to the mouth by the tentacles. The mouth also releases sex cells .
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RELEASING SEX CELLS
Sex cell production: Eggs and sperm are formed in small pink bundles that move up to the mouth of each polyp .
Spawning: All the corals in one reef area release their sex cells simultaneously. The bundles float up and burst, allowing sperm cells to fertilize unrelated eggs.
us P 6001 12054 PACKET 54
The spreading, rounded mass of a brain coral
encompasses a highly complex colony made up of rows
of tiny organisms called polyps. These polyps in turn
harbor microscopic single-celled plants within their bodies.
These plants convert light and carbon dioxide into
nutrients, supplementing the polyps diet of live prey
and helping the coral thrive in warm, clear waters.
~ CHARACTERISTICS Brain corals are widespread in coral reefs in the Caribbean as
well as the tropical Pacific and Indian oceans. The reefs have
developed over millions of years. Living corals grow on
the dead limestone skeletons
of their predecessors, building the reef steadily upward as sea levels rise.
Each brain coral is a colony of tiny, anemonelike organ- .
isms called polyps. A polyp is basically a tube with a crown of stinging tentacles .
The polyps stand in long, meandering lines separated
by grooves, which gives the
whole a fissured appearance resembling that of the human
brain . Each polyp is linked to
the next by a stolon-a thin tube of body tissue that allows
nutrients to pass between in
dividuals . The polyps are also linked by a common nerve network that ensures they all
act in unison. Under the glare of a flashlight, for example,
the polyps simultaneously retract their tentacles.
Right: Tentacles on each polyp inject poison into tiny animals and then pass them to the polyp's mouth.
~ FOOD & FEEDING Brain corals feed at night on
zooplankton, tiny animals in the water. The coral polyps have tentacles that are armed with
barbed stinging cells, or nematocysts. If something bumps
against a tentacle, a sac bursts open and a dart shoots out to inject paralyzing poison into the
victim. The prey is pulled in by the tentacles and passed into the polyp's mouth in the center. Then digestive juices break
down the prey, and the nutri-
Left: Brain corals may share their living space with stag 's horn coral, a treelike species.
ents pass along the connective
paths to feed the whole colony. Brain corals also benefit from
single-celled plants that live within them. These plants absorb sunlight and then use it to turn carbon dioxide and
water into sugars that help nourish the coral. Without this extra food a brain coral can
not grow. If the ocean water becomes cloudy or polluted so sunlight does not reach the
plants, the brain coral dies.
Right: Brain corals live only on shallow reefs, where sunlight activates the plants that feed it.
Left: Lines of tightly packed polyps, with deep fissures in between, grow on this brain coral's upper surface. Underneath the live polyps, the bulk of the coral mound consists of dead polyp skeletons.
DID YOU KNOW? • The coral colony's limestone skeleton has distinct bands like the rings of a tree trunk. Count
ing the bands gives a rough estimate of the colony's age.
• Corals spawn together to thwart predators that eat the
eggs. Although fish in the area eat the eggs rapidly, they stop
~ BREEDING Brain corals reproduce both
sexually and asexually. For sexual reproduction, all the reef's
corals spawn at the same time. For a few days in spring, the
entire reef is flooded with eggs and sperm cells.
Some months before these cells are released, the sex organs
in each polyp begin producing first eggs and then sperm. The
sex cells work their way toward the mouth. At the due time
usually a few nights after a full moon in late spring-bundles of sex cells are released. They
float to the surface and then
when full, and the remaining eggs survive to reproduce.
• Brain corals are preyed on by the crown-of-thorns starfish, which settles on a colony and
digests polyps with its pushedout stomach lining. Starfish
epidemics occur periodically, and many corals are killed.
burst apart. The sperm are pre
vented from fertilizing the eggs they are packed with and drift
off to find other eggs.
When an egg is fertilized by a sperm, it develops into a float
ing larva. This larva eventually
settles on the reef and turns into a single coral polyp. The
polyp then reproduces itself asexually by budding-producing budlike offshoots near
its base, which develop into
new polyps. A whole new network of stolons and polyps is
created, eventually developing into a new brain coral.
CENTIPEDE
ORDER Chilopoda
FAMILY Lithobiomorpha
GROUP 6: PRIMITIVE ANIMALS ... GENERA
"11IIIIIIII Various
Centipedes are agile, venomous predators. They usually eat insects but will devour any animals-including other centipedes
that they can catch and stun with their poison fangs.
CHARACTERISTICS
Length: Average, 1-2 in.
Legs: Common centipede has 15
pairs. Other species have up to
101 pairs.
Mouthparts: Chewing jaws sup
plemented by poison fangs.
BREEDING
Breeding season: Generally spring
to fall in temperate climates.
Eggs: Laid singly in soil or in
batches.
Hatching t ime: About 3 weeks.
LIFESTYLE
Habit: Active at night; solitary.
Diet: Insects, small crustaceans,
worms, slugs, and other centipedes.
Lifespan: Up to 6 years.
RELATED SPECIES
There are about 3,000 species of
centipede found worldwide.
Range of centipedes.
DISTRIBUTION
Centipedes are found worldwide in tropical and temperate
climates. They do not occur in the middle of the Sahara Desert
or in polar regions. The common centipede is found in Europe,
North Africa, and the Americas.
CONSERVATION
Centipedes are under no direct threat from humans. They help
to control garden pests and should not be harmed.
THREE SPECIES OF CENTIPEDES
Necrophlosophagus longicoreis: Spends much of its time burrowing underground. Long, segmented pale body with many pairs of short legs.
J )~
The common centipede, Lithobius forficatus: Molts several times before reaching adult size. Has 30 legs, with longer legs at rear of body. First pair of legs modified into poison claws. Last2 pairs are dragged.
Scutigera coleoptrata: Short body but very long legs for speed. Long, touch-sensitive antennae.
--
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/
0160200501 PACKET 50
Centipedes are found all over the world except in
polar regions and the middle of the Sahara Desert.
They are creatures of the dark, emerging only at
night to pursue their prey over damp earth. As dawn
approaches, they return to their moist dens,
where they hide their flat bodies in crevices
to escape the drying effects of the sun.
~HABITS Centipedes are found in tem-perate and tropical climates worldwide. They are heavily armored with strong plates of chitin, a substance that forms a tough outer skeleton. Insects are also protected by chitin, but they have waterproofing that allows them to live in hot, dry climates without dehydrating. By contrast, centipedes must keep moist to survive.
Centipedes respond to the presence of moisture. They move quickly over dry surfaces and slow down when they come to moist ground. They spend most of their time in
moist places-beneath stones, under logs, in rock crevices, or behind loose bark. Many species spend their lives buried in damp soil. The common centipede comes out at night to hunt among moist vegetation and leaf litter but returns to the shelter of a crevice in daytime.
A centipede's flat, long body is ideally shaped for lurking in narrow gaps. It enters a crevice and crawls forward until its body is wedged in the crack. It often has to emerge backward, guided by the long hindmost pair of legs, which sense obstacles in its path.
~ FOOD & HUNTING All centipedes hunt, preying to sense vibrations from their on insects, spiders, wood lice, potential victims . worms, and slugs . They also Once caught, a victim has feed on other centipedes. no chance of escape. A cen-
Catching prey is rarely a tipede is armed with a pair of problem because most cen- poison fangs that curve for-tipedes are very fast runners . ward toward the front of its Scutigera centipedes have very head. The poison injected by long legs and move so fast these fangs instantly para-that they can even dart up to Iyzes the prey. The centipede flies and catch them . Most then devours the impaled centipedes are almost blind. and stunned creature with its They rely on their antennae powerful jaws.
Left: To find prey, centipedes rely on their touch-sensitive long antennae.
DID YOU KNOW? • The common centipede avoids winter frosts by burrowing deep in the soil. • Some centipedes produce a bright fluid when alarmed. This defense may frighten off predators. • Some tropical centipedes grow up to one foot long and prey on animals like mice and
Right: Centipedes molt many times before reaching adulthood, emerging each time with more legs.
toads. Their venom can be dangerous to humans but is rarely fatal. • If a centipede loses a leg, it grows another. The new leg gets longer every time the centipede sheds its skin. • Centipedes produce formic acid, "Yhich is the same chemical as scorpion venom.
[ J NATUREWATCH Centipedes rarely emerge in daylight. But you may find one in a garden if you disturb the soi l. The common centipede likes dark, moist areas and may be found under a large stone or log . When disturbed, it runs with surprising
~BREEDING Attracted to a receptive female by scent, the male centipede first circles her. Then he spins a pad of silk on the ground and places a package of sperm on it. The female walks over the package and picks it up using a pair of claspers at her hind end. Claspers are almost the only way to tell the sexes apart.
If the female gathers the sperm in spring or summer and places it on her sex organs, her eggs are fertilized almost immediately. If she mates later in the year, she
Left: The female giant Scolopendra wraps around her eggs to protect them.
speed to a new hiding place. Watch a centipede move.
As it lifts one leg after another, waves of motion ripple down along its legs. Each side moves alternately; while one side is active, the other side stays still.
carries the sperm in her body for months before laying eggs. The common centipede lays eggs singly in the earth and leaves them to develop on their own. In many other species, the female lays batches of eggs, which she cleans and guards.
A newly hatched common centipede has fewer body segments than an adult and only 12 legs. It sheds its skin several times, growing more legs at each molt. A common centipede may molt four times before it has all 30 legs. It may be two years old before it is ready to mate.
SEA SQUIRT
Sea squirts spend their adult lives glued to rocks. Although they look more like plants than animals, sea squirts are related to
some of the most complex animals on the planet.
SIZES In a star sea squirt colony, each individual is about ~6 in. long, and the cluster is about 1,1.; in. across.
The clusters are grouped in patches up to 6 in. across.
BREEDING Each individual is both male and female and produces a few large eggs that are fertilized either internally or externally. Mobile larvae colonize new sites.
LIFESTYLE Habit: Adult is sedentary and attached to rocks or the anchors
of large seaweeds. Diet: Floating organic debris, microscopic animals and plants.
Lifespan: About a year.
RELATED SPECIES There are about 2,000 species of sea squirt worldwide. Their nearest relatives are the similar but
free-floating salps.
ANATOMY OF A SEA SQUIRT
Heart ---+--HoiliH4
Adhesive base
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Range of sea squirts.
DISTRIBUTION The star sea squirt is usually found in shallow coastal waters up to the low-tide line in temperate, plankton-rich seas. Other species may be found in deeper waters, where they
feed on decaying matter.
CONSERVATION Sea squirts on coasts are vulnerable to pollution from oil and chemicals. But in general, sea squirts are not in danger.
Nerve cord Intestine Pharynx
Adhesive papillae
Larva: Shaped like a tadpole. Swims around until it finds a place where it can settle and transform into an adult sea squirt.
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Some species of sea squirt are single individuals.
Other species are small colonies of individuals that are
arranged in clusters like the petals of a flower. Found on
rocky shores, sea squirts form crusts on rocks in sheltered,
permanently moist places. They live on tiny food
particles that they filter from the water.
~ HABITAT On land, most animals have to
move around to find food. But
in the sea, the food itself is on
the move. Suspended in the
dense salt water, millions of
microscopic life forms ebb and
flow with the currents in clouds
of organic debris.
With so much edible matter
floating by, small marine ani
mals can easily snare any food
that happens to drift past. Since
they don't have to move in
order to find food, animals like
sea squirts can remain attached
to rocks and still survive.
Although they resemble blobs
of jelly, sea squirts are not as
primitive as they seem. A sea
squirt larva has a nerve cord
that runs down its body and a
muscular tail supported by a
crude backbone. The anatomy
of this tadpolelike larva indi
cates that it is related to fish,
reptiles, birds, and mammals.
~ CHARACTERISTICS A sea squirt is basically a tube
of jellylike matter with water in
side. When it is touched, a sea
squirt will live up to its name by
squirting water.
Some sea squirts live indepen
dently, while others live in large
colonies. The star sea squirt,
for example, is a colony. Each
"star" is a cluster of individual
tubes embedded in a jellylike
mat that is shared with other
clusters. The arrangement re
sembles daisies scattered over
a rock and sealed in a layer of
transparent wax.
Each individual lives by taking
in water at one end of the tube,
drawing it through a fine filter
to strain out the edible particles,
and pumping the water out the
other end.
In solitary sea squirts, which
stand upright on their rocks,
the exhaust end of the tube is
a spout on the side of the ani
mal's body, like the spout of a
teapot. In star squirts, which lie
Left: Sea squirts pump water in through their large upper opening. Here they are grouped on the Mediterranean seabed.
~ BREEDING Sea squirts have both male and
female sex organs, so in theory
they could fertilize themselves.
But they exchange sperm in
stead, so each offspring con
tains the genes of two parents.
This provides for variation and
allows the species to evolve.
Some sea squirts release both
eggs and sperm into the water,
where they mingle and join
to form floating embryos. Star
sea squirts keep their eggs, and
on their backs radiating from a
central point, the water is ex
pelled from the center of the
star along with waste products.
The food filter is actually
the upper end of the intestine.
Water that is drawn into the fil
ter escapes through perfora
tions into the body cavity to be
pumped away. The food parti
cles stay inside, held by the filter
and a sticky mucus that flows
down into the digestive tract,
they fertilize them by drawing
in sperm with their food. The
embryos then develop into lar
vae in the parent's body.
Sea squirt larvae are free
swimming creatures that re
semble tiny tadpoles, with
rounded bodies and long tails.
Each larva drifts in the current
until it is almost mature. Then it
uses a sucker on its head to
attach itself to a rock where it
changes into its adult form.
taking the food along with it.
The food filter also acts as a
gill, absorbing oxygen from
the water that flows through
the animal. The water flow is
maintained by the constant
motion of tiny hairs called cilia. As a result, sea squirts can get
enough oxygen, even though
they live in places with very lit
tle natural water movement.
Below: Sea squirts gathered on Australia's Great Barrier Reef.
DID YOU KNOW? • A common sea squirt can filter over 200 quarts of wa
ter an hour when feeding.
• Most sea squirts live in shallow, food-rich waters,
but some live in the deep
oceans, more than 16,000
feet beneath the surface.
There they feed on decay
ing animal fragments that
drift down.
• Some sea squirts attach
themselves to the under
water structure of oil rigs
and to the hulls of ships.
• Some sea squirts can
reproduce by simply pro
ducing extra individuals on
the sides of their bodies.
~ NATUREWATCH Species like the star sea
squirt are found on rocky
seashores below the low
tide mark, beneath rocks,
or under wet seaweed.
Since sea squirts need
constant moisture, they
must be covered after
being examined, or they
may dry out and die.
On exposed shores the
colonies cover rocks, but
in sheltered waters they
can form freestanding
fleshy lobes. Star clusters
may be yellow, orange,
blue, or white, with a
bright red spot at the
tip of each sea squirt.
Left: These sea squirts have translucent bodies that reveal their internal organs. Individual sea squirts can be up to four inches long.
COMMON CUTTLEFISH
PHYLUM Mollusca
CLASS Cephalopoda
... ORDER ~ Sepioidea
... GENUS & SPECIES ~ Sepia officinalis
The common cuttlefish hunts for prey at night, snatching its victims with its two long hunting tentacles. During the day it hides,
changing the color of its skin to match its surroundings.
KEY FACTS
SIZES
Length: 1 ft. Hunting tentacles: Up to 1 ~ ft .
long.
BREEDING
Spawning season: Spring and
summer.
No. of eggs: About 300.
LIFESTYLE
Habit: Sociable; swims in shoals.
Preyed upon by dolphins, por
poises, sharks and other fish.
Diet: Fish, crabs, shrimps, and
prawns.
RELATED SPECIES
There are about 80 species of
cuttlefish ranging in size from 2
in. to 5 ft. The cuttlefish belongs
to the class Cephalopoda and is
related to the nautilus and the
other tentacled marine animals,
octopuses and squids.
Range of the common cuttlefish.
- DISTRIBUTION
Found in the North Sea, English Channel, Atlantic Ocean, and
Mediterranean Sea.
CONSERVATION
The cuttlefish is in no danger. It is not generally fished for sport but
is sometimes caught for eating in Mediterranean areas. During the
spawning season, a female may be hooked and towed below the
surface to attract males. Then all the fish are netted.
FEATURES OF THE COMMON CUTTLEFISH Skin: Contains hundreds of pigment cells that can be contracted or expanded to change color within seconds. Color change provides the cuttlefish with camouflage and is also used in courtship.
THE CUTILEBONE
A soft, chalky internal shell that supports the soft parts of the body.
Eyes: Large, W~it:ll~~~II'~~~rli all-round vision. Rapidly send information to the brain.
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Tentacles: Eight short tentacles are used to sense surroundings, to protect the head, and to hold prey when feeding.
Two longer tentacles are used in hunting. The male cuttlefish has one ten
tacle modified for transferring sperm.
0160200461 PACKET 46
Along with the octopus and the squid, the common
cuttlefish belongs to the class Cephalopoda-
the most highly evolved group of mollusks. Equipped
with strong tentacles and sharp eyes that can see in all
directions, the cuttlefish is a match for prey and predators
alike. It can even shoot backward out of danger by
using an advanced jet propulsion system.
~ HABITS The common cuttlefish is most
often found in shallow sea wa
ters with a sandy bed. It hides
during the day, changing color
to match its surroundings, and
hunts for prey at night.
The internal shell of the cut
tlefish is porous and holds both
water and a mixture of gases.
By controlling the amount of
gas or water in its shell, the cut
tlefish can sink to the seabed
and rest on it, or it can remain
afloat at any depth.
I DID YOU KNOW? • A cuttlefish can color 26 cubic yards of water with its
ink in a few minutes.
• The ink produced by cuttlefish has been used byart
ists for centuries to make a
rich brown pigment known
as sepia. • A cuttlefish can regenerate a lost tentacle.
~ FOOD &: HUNTING At night the cuttlefish hunts for
fish, crabs, prawns, and shrimps.
Its large eyes let it see prey from
any direction, even behind.
Moving slowly forward by rip
pling its lateral fins, the cuttle
fish extends its eight suckered
tentacles. Two longer tentacles
with suckered ends shoot out
and grab the prey, which is
drawn into the mouth and bro
ken up by the cuttlefish's beak
like jaws.
Left: Gentle undulations of the lateral fins propel the cuttlefish through the water.
Right: The cuttlefish snatches prey such as prawns with its long, suckered tentacles.
• Schools of badly mangled cuttlefish often wash ashore,
but it is not known what
causes this.
• During the mating period, • the female cuttlefish is said
to be luminous.
• With its highly developed brain, the cuttlefish can
learn by experience.
Left: When courting a female, the male cuttlefish displays zebralike stripes.
~ ~ SPECIAL ADAPTATIONS The common cuttlefish has
ingenious devices for fooling
predators and prey. While it
hunts, it constantly changes
color to blend in with its sur
roundings. Entire shoals can
change color in unison.
To escape from predators,
~ BREEDING During spawning season, the
male cuttlefish displays yellow
ish white and purplish brown
stripes. When another cuttlefish
Left: The young cuttlefish breaks free from the egg when it is less than halfan inch long. Fully mobile, it swims around and preys on tiny plankton.
the cuttlefish emits a jet of
water from its siphon (a spe
cial funnel on the underside)
and shoots backward, away
from danger. At the same
time the cuttlefish may re
lease a"n inky fluid that con
ceals it from enemies.
approaches, he displays his hectocotylus, a modified tentacle
that carries his sperm. If the sec
ond fish does not do the same,
the male knows it is a female.
He then uses this tentacle to
place sperm in a pouch below
the female's mouth, which con
tains the reproductive organs.
The female lays about 300
eggs in batches of 20. Each egg
is coated with a rubbery black
solution and has a long tail that
attaches the egg to a plant stalk.