on cephalopods
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On Cephalopods. By Claire and Asparaguy. What is a cephalopod?. 1: Pfeffer’s Flamboyant Cuttlefish ( Metasepia pfefferi ) 2: Bigfin Reef Squid ( Sepioteuthis lessoniana ) 3: Greater Blue-Ringed Octopus ( Hapalochlaena lunulata ) - PowerPoint PPT PresentationTRANSCRIPT
On CephalopodsBy Claire and Asparaguy
Can you identify these cephalopods? :D
What is a cephalopod? 1: Pfeffer’s Flamboyant Cuttlefish (Metasepia pfefferi)
2: Bigfin Reef Squid (Sepioteuthis lessoniana)
3: Greater Blue-Ringed Octopus (Hapalochlaena lunulata)
4: Shells of various species of nautiloids (Nautilus macromphalus, Allonautilus scrobiculatus, and Nautilus pompilius)
5: The Dumbo Octopus, Grimpoteuthis.
1 2 3
4 5
A cephalopod is a member of the class Cephalopoda (phylum Mollusca) Bilateral body symmetry Prominent head Set of tentacles or arms (number and type varies) Ability to squirt ink
Cephalopod is Greek for “head-footed” Two subclasses (Coleoidea and Nautiloidea)
Overview of the cephalopods
Overview of the cephalopods
The most intelligent invertebrates Most have well-developed eyes All cephalopods are active predators Move by jet-propulsion – expelling water at high
speed through a hyponome. Most possess an ink sac which produces brown
or purplish ink that is used to ward off attackers.
Image from Clarkson
Simplified evolution of the extant cephalopods!
Arms Beak Hyponome Digestive tract Gills Internalised shell Mantle
Tentacles Shell Gills Siphuncle
Septum Umbilicus Camerae
Hyponome
Tentacle Stomach Caecum Heart
The ink of cephalopods: When combined with less mucus, simply acts as a
smokescreen to interfere visually with the predator The ink’s tyrosinase may also irritate or inactivate
the chemosensory systems of the predator. When combined with large amounts of mucus, it
forms a pseudomorph.
Overview of the cephalopods
The beak of cephalopods: Chitinous structures shaped like a parrot’s beak Formed by the gradual hardening of tissues Muscle around the beak is known as the buccal
mass; also contains radula (a rough tongue)
Overview of the cephalopods
Shells of the cephalopods: Nautiluses retain an aragonitic external shell. Squids have the squid pen or gladius. Cuttlefish have a porous, aragonitic cuttlebone. The shell is completely absent in most octopuses.
Overview of the cephalopods
Cephalopod locomotion: Squids move by drawing water into their mantle
cavities and expelling it through their funnels. Octopuses use the suckers on their arms to move
about on the seafloor. Cuttlefish undulates the fin fringe running along
their mantles in addition to jet-propulsion (gas filled cuttlebone provides buoyancy)
Some squids, such as Ommastrephes bartramii, the neon flying squid, can “fly”!
Overview of the cephalopods
Cephalopod locomotion: The mantle is made of longitudinal and circular muscle fibres. The circular muscles relax, expanding the mantle cavity. The circular muscles then contract, sealing the opening. The longitudinal muscles contract and expel the water.
http://www.biology.ualberta.ca/courses.hp/zool250/animations/Squid.swf
Overview of the cephalopods
Squids such as the neon flying squid, or even the “jumbo” squid (Humboldt squid) can propel themselves out of the water and stabilise their flight with their fins.
Overview of the cephalopods
The cephalopod nervous system
Cephalopods (esp. coleoids) are known to be the most intelligent invertebrates. Spatial learning capacity Navigational abilities Predatory techniques
Nervous system affects chromatophores
The cephalopod nervous system
The squid giant axon: Up to 1 mm thick Unmyelinated, unlike in vertebrates Branches out from the stellate ganglion Innervates the mantle of the squid Responsible for mantle contractions – thus, forcing
water through the hyponome. http://www.youtube.com/watch?
v=omXS1bjYLMI
The cephalopod nervous system
The squid giant synapse: Largest chemical junction in nature Identified by J. Z. Young in 1939 Lies in the stellate ganglion A chain of three neurons Relays input from cephalic ganglion (the squid’s
brain) to the mantle.
The cephalopod nervous system
The cephalopod nervous system
The cephalopod circulatory system
A closed circulatory system Relies on haemocyanin rather than
haemoglobin to transport oxygen Colourless blood turns blue when exposed to air
Coleoids (squids, cuttlefish and octopuses) have two branchial hearts (also known as gill hearts) and one systemic heart which pumps blood around the body.
Note copper prosthetic groups coordinated by histidine residues.
In environments with low temperature and low oxygen pressure, haemocyanin is more efficient than haemoglobin.
Haemocyanin is not bound to red blood cells, but rather are suspended in the haemolymph.
The cephalopod circulatory system
Chromatophores
Soft-bodied cephalopods rely heavily on camouflage to escape detection by predators
Colour patterns of cephalopods are largely controlled by chromatophores in the dermis
Each chromatophore is a miniature organ consisting of a single pigment-filled saccule and numerous muscle, nerve, glial and sheath cells
Chromatophores
Chromatophores
Melanin pigments are yellow, orange, red or brown
Saccules darken with age, presumably due to increased zinc content
When attached muscles contract, the pigment-containing saccule will stretch to cover a larger area, displaying the pigment
Relaxation of muscles causes the saccule to shrink, hiding the pigment
Chromatophores
Each chromatophore is directly controlled by the brain (via associated neurons), enabling: Generation of complex patterns Extremely rapid response to stimuli
The cephalopod eye
Most sophisticated of all invertebrate eyes As complex as and structurally similar
vertebrate eyes (single-lens), but not homologous
During organogenesis, the vertebrate eye develops as an extension of the brain
The cephalopod eye develops from the head surface
The cephalopod eye
Vertebrate (human) eye Cephalopod (octopus) eye
The cephalopod eye
Able to detect polarised light
Hunting prey – light becomes polarised when reflected off fish scales
Covert communication using patterns of polarised light on their skin
Photoreceptors in a cephalopod eye
The cephalopod eye
Octopus Squid Cuttlefish Nautilus
The squid and the cuttlefish
What are the differences? The squid is of the order Teuthida; the cuttlefish is
of the order Sepiida. The squid is torpedo-shaped; the cuttlefish is
broader and more flattened. The squid has a chitinous squid pen; the cuttlefish
has a porous cuttlebone. The squid moves much more swiftly than the
cuttlefish, which relies more on camouflage.
The squid and the cuttlefish
Interesting squid facts: Deep water squid have the second greatest known
penis length relative to body size The squid systemic heart has 3 chambers. Squid ink is used in making Arròs negre. Some male squids can detach an arm and use it to
transfer sperm to the female.
The squid and the cuttlefish
Interesting cuttlefish facts: All cuttlefish contain neurotoxins. Cuttlefish have some of the largest brain-to-body
size ratios. The colour name sepia comes from the Greek and
Latin word for “cuttlefish”. Lateral lines allow it to detect sound – it can hunt
with 50% accuracy in total darkness The Pfeffer’s Flamboyant Cuttlefish is as toxic in
its muscles as the Blue-Ringed Octopus.
The squid and the cuttlefish
Interesting squids: Colossal Squid (Mesonychoteuthis hamiltoni) Crachiid Squid (family Cranchiidae) Cock-eyed Squid (family Histioteuthidae) Promachoteuthis sulcus Piglet Squid (Helicocranchia sp.) Firefly Squid (Watasenia scintillans)
The squid and the cuttlefish
The bobtail squid
Closely related to cuttlefish Rounded mantle and no cuttlebone Symbiotic relationship with bioluminescent
bacteria, Vibrio fischeri. Certain species bury themselves in sand.
http://www.youtube.com/watch?v=eB-M4adJIeY
The octopus
Interesting octopus facts: Chemoreceptors on suction cups allow them
to taste what they are moving across Most are semelparous and exhibit unnatural,
non-coordinated behaviour (senescence) after mating, eventually starving to death This is controlled by endocrine secretions
from the optic glands
The octopus
Interesting octopuses:
Blanket Octopus (Tremoctopus spp.) Vulcanoctopus hydrothermali Paper Nautilus (Argonauta spp.) Mimic Octopus (Thaumoctopus mimicus)
The nautilus
Interesting facts about nautiluses: Two pairs of gills; thus called tetrabranchs. Shell is an example of logarithmic spiral. Considered living fossils Radula have nine teeth. The osmena pearl is derived from the shells. Lifespan of up to twenty years.
The nautilus
Thank you!! :DDD
Um.