hydra, jellyfish, coral, & sea anemones - bpums · hydra, jellyfish, coral, & sea anemones....
TRANSCRIPT
I. radial symmetry
II. dimorphic development
III. nematocysts, specialized organelles produced by cnidocytes
General Characteristics
• They are radially symmetrical; oral end terminates in a
mouth surrounded by tentacles.
• They have 2 tissue layers
• Outer layer of cells - the epidermis
• Inner gastrodermis, which lines the gut cavity or
gastrovascular cavity (gastrodermis secretes
digestive juices into the gastrovascular cavity)
• In between these tissue layers is a noncellular jelly-like
material called mesoglea
Cnidarian Body Plans
Polyp form
• Tubular body, with the mouth directed upward.
• Around the mouth are a whorl of feeding tentacles.
• Only have a small amount of mesoglea
• Sessile
Medusa form
• Bell-shaped or umbrella shaped body, with the mouth is directed downward.
• Small tentacles, directed downward.
• Possess a large amount of mesoglea
• Motile, move by weak contractions of
body
Tentacles
• Have nematocysts (stinging cells)
• Coiled thread discharges like a harpoon
• Contains neurotoxin
• Paralyzes prey
Stinging Organelles
• Prey capture is enhanced by use of specialized stinging cells called
cnidocytes located in the outer epidermis.
• Each cnidocyte has a modified cilium - cnidocil, and is armed with
a stinging structure called a nematocyst.
• The undischarged nematocyst is composed of a long coiled thread
• When triggered to release, either by touch or chemosensation, the
nematocyst is released from the cnidocyte and the coiled thread is
everted
• Some nematocysts function to entangle the prey; others harpoon
prey and inject a paralyzing toxin
Feeding
Lion’s mane eats another jelly
Carnivores (predators)
Process of feeding
1. Tentacles sting prey with nematocysts
2. Tentacles grab prey
3. Prey pulled into mouth
4. Prey stuffed into gastro-vascular cavity (GVC)*
5. GVC makes enzymes, extra-cellular digestion
6. Undigested food back out mouth
*incomplete digestive tract (no anus)
Nutrition
• Cnidarians are carnivores with hydras and corals consuming plankton and some of the sea anenomes
consuming small fishes
• They use tentacles to capture prey and direct it toward the mouth so that it can be digested in the
gastrovascular cavity via secretions from gland cells (extracellular digestion); some food is phagocytized by
special cells and digestion occurs intracellularly
• The gastrovascular cavity exists as 1 opening for food intake and the elimination of waste
• There is no system of internal transport, gas exchange or excretion; all these processes take place via
diffusion
Response
Sensory cells
1. Chemoreceptors (chemicals)
2. Thigmoreceptors (touch)
3. Photoreceptors (light)
Ocelli (eyespots)
4. Statocysts (balance)
Locomotion
A. Medusa motile, free-swimming
A. Polyps sessile
Exceptions:
1. Hydra tumbles on tentacles
2. Sea anemones glide on pedal disc
Reproduction
1. Asexual
budding from polyps or medusa
2. Sexual
a. Medusae release sperm & eggs
b. Some monoecious, some dioecious
Larvae free-swimming
CNIDARIA
Phylum:
Cnidaria: (formerly called Coelenterata)
Class:
I. Hydrozoa: (hydroids)
II. Scyphozoa: (jellyfish)
III. Anthozoa: (corals)
Phylum: Cnidaria
Class: Hydrozoa: (hydroids)
the most part colonial species that have alternating medusa and polyp stages
This order has a chitinous exoskeleton
Hydrozoa are colonial and create an aragonite (calcium carbonate based) skeleton
The best known of these complex colonial organisms is the Portuguese man-of-war (Physalia physalis).
Phylum: Cnidaria: (formerly called Coelenterata)
Class:
Scyphozoa: (Jellyfish)
The class Scyphozoa is generally characterized by having a much larger medusa stage than polyp stage
Class Anthozoa: Anemones & Corals
• Appear like plants but are animals.
• Polyp form is dominant.
• Corals build calcium shells to protect themselves
• Have symbiotic relationship with algae.
• Can build extensive masses which can form land
masses.
Anemone
Coral Polyps
Class Anthozoa
• Exclusively marine; there is no medusa stage
• At one or both ends of the mouth is a ciliated groove called the
siphonoglyph; generates a water current and brings food to the gastrovascular
cavity
• Possess a well developed pharynx
• The gastrovascular cavity is large and septa or
mesenteries; increase surface area for digestion
or support
Class Anthozoa
Corals obtain much of their energy from microscopic photosynthetic algae (zooxanthellae) or dinoflagellates
that live symbiotically inside the cells of the coral
Zooxanthallae is a genus among the Dinoflagellata
It will loose its flagella and live in the tissue of corals
Phylum: Cnidaria
Class: Anthozoa: (corals)
In general, the class is comprised of the vast majority of species commonly referred to as sea anemones
and corals.
existing exclusively as polyps, completely without a medusa life stage
Anthozoa into three subclasses:
I. Octocorallia,
II. Hexacorallia,
III. Ceriantipatharia
Class: Anthozoa: (corals)
Sub class: Octocorallia (Soft corals)
Octocorallia: commonly known as soft corals
not very closely related to the true corals (Scleractinia)
The polyps of octocoralliarians have eight tentacles
divided into five or six orders (Telestacea, Alcyonacea, Gorgonacea, Pennatulacea, Helioporacea, and
sometimes Stolonifera)
(blue coral)Tubipora musica
Colony shape: bushy
Habitat : depth above 10 , with clear water ( visibility 8 m)
Family Plexauridae :
Dendronepthya sp. Kukenthal, 1905
Class: Anthozoa: (corals)
Sub class: Octocorallia
Most do not develop skeletons
Most octocorals form spicules within their tissues, and some produce calcified holdfast structures or long, rodlike
internal supports.
All of the octocorals are colonial, including the sea fans and sea whips (Gorgonacea).
The scleractinians are the largest group of anthozoans, with approximately 3600 extant species
This prominent taxon provides the calcium carbonate building blocks for the world’s coral reefs
calcium carbonate skeleton is secreted by the epidermis and is present in all members of this order
The order Scleractinia is usually divided into 18 families
Class: Anthozoa: (corals) Sub class: Hexacorallia
Order: Scleractinia (True Stony Corals)
Class: Anthozoa: (corals) Sub class: Hexacorallia
Order: Scleractinia (True Stony Corals)
Scleractina are classified by morphological features of colony growth and various soft-tissue features
The Acroporidae are mostly in two genera, Acropora and Montipora. These are fast-growing forms with both asexual
and sexual reproduction.
Some scleractinians, like members of the genus Fungia, are solitary and can be relatively large: up to 50 cm in diameter
FungiaAcropora nasuta Montipora capricornis
Class: Anthozoa: (corals)
Sub class: Hexacorallia
Hexacorallia is comprised of six orders, two of which are extinct, order Rugosa and Tabulata.
I. order: Actinaria : sea anemones
II. order: Zoanthidia : colonial anemones
Class: Anthozoa: (corals) Sub class: Hexacorallia
Order: Actinaria (sea anemones)
I. Most of the soft-bodied anthozoans known as sea anemones are classified in the Actinaria
II. Actinarians generally have column-shaped bodies with the mouth at one end and a muscular pedal disk for
attachment to substrates at the other.
I. Actinarians have soft bodies and do not form hard parts, some coat themselves with sand grains and/or
mucuslike secretions.
Class: Anthozoa: (corals) Sub class: Hexacorallia
Order: Actinaria (sea anemones)
I. Most actinarians are relatively sessile, either not moving or moving very slowly by contractions of the
pedal disk
II. Some anemones burrow into sand, and a few can swim short distances
III. Actinarian anemones can reproduce either sexually or asexually
IV. They do not form true colonies with permanent tissue connections between members, as seen in the
superficially similar zoanthiniarian anemones
Class: Anthozoa: (corals)
Sub class: Hexacorallia
Order: Zoanthidia
Small group of polypoid anthozoans that differ from most sea anemones (Actinaria) in details of internal
anatomy.
unlike most sea anemones, zoanthiniarians can form true colonies in which all members are connected by
common tissue.
Zoanthiniarians make no hard parts and leave no fossil record
However, they are more closely related to extinct coral taxa (Tabulata and Rugosa) than they are to other
soft-bodied anthozoans
Class: Anthozoa: (corals)
Sub class: Hexacorallia
Order: Zoanthidia
Sub order: Brachynemina
Family: Zoanthidae
Genus: Zoanthus
This taxon is often referred to as intermediate in form between hard corals (Scleractinia) and sea anemones
(Actiniaria), as most species lack a skeleton and yet are colonial.
Zoantharians are widely distributed and are particularly common in subtropical and tropical regions, where
they are one of the major benthic components of coral reefs.
Some species contain unique chemicals such as palytoxin or norzoanthamine
Where seen?
Genus: Zoanthus
Like a carpet of tiny flowers, these animals are often seen on:
I. shores,
II. growing on stones
III. as well as under seagrasses in vast seagrass meadows.
IV. They may form a dense carpet that covers large areas of several square metres
Genus: Zoanthus
What do they eat?
Zoanthus spp. do not need to be fed directly, since they obtain much of their nutritional requirements
from their symbiotic zooxanthellae.
They must therefore be provided with adequate illumination to thrive.
They also ingest dissolved organic substances from the water, as well as fine particulate matter.
Some species do not take large particles of food, while others do take and eat such things as flake
food, blackworms, shrimp, and sea urchin eggs.
Zoanthids mainly reproduce asexually, although there is a limited amount of sexual reproduction
Genus: Zoanthus
Zoanthids differ from true sea anemones, which belong to the subclass Actiniaria, based on details of
their internal anatomy and the fact that zoanthids form true colonies in which the individual polyps
are connected by a common tissue, the coenenchyme.
Members of this genus are the most colourful of the zoanthids, being shades of green and brown
typically, but sometimes fluorescent red, orange, pink, blue, yellow, or gray, and usually two-toned
Genus: Zoanthus
These Anthozoans consist of a skeleton made from detritus and sand particles which is not hard enough to
sustain the currents, but it definitely helps in forming huge colonies in areas with high sediment rates.
The zoanthids form a major constituent of the rocky intertidal macro benthos
Genus: Zoanthus
Zoanthus sp. have soft bodies covered with a leathery skin, called the cuticle, which gives them
protection.
Their polyps have fairly short stalks topped with a small flat oral disc.
Tentacles radiate from the outside of the oral disc and are usually expanded day and night.
The results of the present study show that the nucleotide sequence of this mitochondrial gene fragment
is identical in all the examined samples and is consistent with the reported sequences of the species of
Zoanthus sansibaricus.
What this study obtained is undoubtedly a systematic report from the color variation of the available
samples in the Iranian islands of the Persian Gulf. Observation of brown, green, gray, red, pink and
purple polyps, green and brown tentacles, green, red, blue and pink oral color with oral disc green,
red, blue, pink and gray colors confirms a wide range of colors in this species.
Morphological and Genetic studies of Zoanthid Genus Zoanthus in some coral islands of the Persian Gulf: Qeshm, Larak and Kish
Atoosa Noori Koupaei* , Pargol Ghavam Mostafavi , Jalil Fallah Mehrabadi , Seyed Mohammad Reza Fatemi
Using in situ field examination integrated with 16S rDNA sequencing and phylogenetic analysis
In this study, diversity of shallow water zoanthids off the Qeshm Island, the largest island in the
Persian Gulf, was investigated for the first time.
the presence of three zoanthid species in the inter-tidal and shallow water zone of Qeshm
Island were demonstrated
Zoanthus sansibaricus (n = 12) with five morphotypes,
Palythoa cf. mutuki (n = 10) with two morphotypes
Palythoa tuberculosa (n = 4) with just one morphotype.
Natural Products Isolated from the Order Zoantharia
1. Zoanthusterone : is a representative ecdysteroid isolated from a Zoanthus
2. Prostaglandins like PGA2 : isolated from Palythoa
3. zoanthoxanthin: natural products based on the highly fluorescent
4. parazoanthoxanthin A : has shown significant anticholinesterase activity
5. Palytoxin