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Sea Star

A presentation about Sea Stars and their phylum, Echinodermata.
by

Anna G.

on 23 June 2011

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Transcript of Sea Star

Sea Stars By Anna Giesler Echinodermata Phylum Examples of organisms within this phylum are: Sea Cucumbers
Sea Urchins
Sand Dollars
Brittle Stars
Feather Stars
Sea Stars
Sea Lilies
Sea Daisies Ecinodermata- From the Greek meaning "spiny skin". Sea Star Research Phylum Diversity Within the phylum echinodermata, there are about 7,000 described living species and about 13,000 extinct species that are know from the fossil record. They are the largest phylum without any freshwater or terrestrial forms. Sea Cucumbers Sea Urchins and Sand Dollars Brittle Stars Sea Lilies and Feather Stars Sea Daisies -Soft-bodied, sluglike animals without arms
-Ossicles are small and not fused together
-Tough, leathery exterior
-They feed by trapping tiny organisms in the sea water
-Tube feet modified into tentacals which are covered with a sticky mucus that entraps plankton
-When threatened, a sea cucumber can release a number of sticky threads from its anus to entrap its attacker -Along with sea baskets, they make up the largest class of echinoderms
-Slender branched arms that move in pairs to row along the ocean floor
-Their arms break off easily, which gives brittle stars their name
-Live primarily on the ocean bottom, and usually hide under rocks or within crevices in coral reefs
-Most species are filter feeders or feed on food in the ocean sediment, but a few species are predators
-Have flexible arms for crawling -Were discovered in 1986
-They are less than 1 cm in diameter
-Disk-shaped little animals
-Only a few species are known
-Have a five-part radial symmetry but no arms
-Have tube feet which are located around the edges of the disk, rather than along the radial lines like they are in other echinoderms -Most primitive and ancient living echinoderms
-Mouth is located on their upper surface rather than lower like other echinoderms
-Sea lilies are sessile and are attatched to the ocean floor by a stalk about twenty-three inches long
-Feather stars use hooklike projections to anchor themselves directly to the ocean bottom or a coral reef
-Sometimes feather stars crawl or swim for short distances
-Filter feeders with oral side up with arms outstretched -Lack distinct arms but have the basic five-part body plan
-Have a hard, somewhat flattened endoskeleton of fused plates that are covered with protective spines protruding from it
-In some species of sea urchin, the spines contain a venom that causes a severe burning sensation while other species have a specialized type of pedicellarium which contains a toxin used to paralyze prey
-Sea urchins are found on the ocean bottoms and sand dollars live in sandy areas along the sea coast
-Urchins move by means of tube feet and moveable spines
-Sand dollars use spines to bury into the sand Sea Stars *See sea star research Five living classes: Asteroidea, Crinoidea, Echinoidea, Holothuroidea, and Ophiuroidea. They are mainly a marine group and found in all oceans. Phylum Habitat A few species live in brackish waters, but other than that all echinoderms are benthic organisms found in marine environments. Inhabit depths ranging from shallow waters at tide lines to the deep sea. Class Asteroidea Seven orders: brisingida, forcipulatida, notomyotida, paxillosida, spinulosida, valvatida and velatida Examples of organisms Cusion Stars
Sea Stars *See sea star research Sea Star Cushion Stars How Organsisms in Echinodermata Feed and Digest Food Suspension Feeders- Sea Lilies and Feather Stars
-They actively capture food particles in the water that travel in close proximity by using (stinging) tentacles. They are also filter feeders. There are about 2,000 different sea star species. Habitat Diet Numbers -Inhabitats depths ranging from shallow waters at tide lines to the depths of deep seas.
-Present in all oceans. They are carnivores and feed on mussels, clams, barnacles, sea urchins, snails, and a few species eat other sea stars. Reproduction Adaptations Importance In The Environment: How It Fits In Unique Features Current Scientific Research Being Done -Sexes are separate
-May reproduce sexually or asexually
-To reproduce sexually, the male and female release gametes into the water where they will meet and the sperm will fertilize the egg, which will settle at the bottom of the ocean to develop.
-To reproduce asexually, a sea star regenerates part of its body. It may be an arm, or it may be an entire sea star if part of the central disc is attached. -Regeneration of body and/or arms: If a predator comes along and starts attacking a sea star and takes an arm off, the sea star could regrow that as long as a portion of the central disc was still intact. And if there was a portion of the central disc with the arm, that arm could give rise to a whole new sea star. This is also part of asexual reproduction.
-Sea stars have rows of spines on their topside to protect against predators.
-Sea stars have tube feet on their oral surface which is used for movement and to cling to surfaces in the ocean.
-The sea star has two stomachs. It can push one of these stomachs outside of its' mouth to engulf prey or insert it into prey (between to shells, for example).
-Sea stars DO NOT have blood. Instead, they use seawater and a fairly complex water vascular system to keep moving things.
-Sea stars do not have gills or lungs, they rely on diffusion across surfaces in their body. Most of this oxygen intake in from water that passes over their tube feet.
-They have a chemical in them wich acts a defense system. If a predator were to bite into them, they would probably spit it out because it tastes so bad. One tropical species, the
crown-of-thorns, has so many chemicals that if you touch it, you will get a nasty burn just from the sea stars chemical defenses.
-In addition to chemical defenses, they use chemicals to detect prey and other objects in the water. Body Plan and Structure -Invertebrates
-Have a skeleton beneath their skin, which is not movable.
-Have a five-part (may be more or less) radial symmetry as adults and bilateral symmetry as larvae.
-They have a nerve net, which means that their nerves are spread all across their body.
-The mouth is located on the oral side of the sea star and the anus is located towards their aboral side.
-The madreporite is located on the aboral surface. This structure acts as a water filter and supplies their water vascular system with water to move.
-They have two stomachs- the pyloric stomach and the cardiac stomach- located around the anus as part of the central disc.
-The cardiac stomach can be pushed out of the sea star's body to engulf and digest food.The pyloric stomach digests the food even more turning it to waste which is then excreted through the anus.
-Sea stars have a simple eye spot at the end of each arm used in detecting differences in light.
-Pedicellariae are tiny pincers that grasp objects and help clean debris and parasites from the body.
-Tube feet that allow movement. -Able to push their cardiac stomach out of their mouth.
-Two stomachs.
-Able to regenerate a whole new sea star from a single arm.
-Bony, calcified skin to protect from predators.
-Water vascular system
-Use sea water instead of blood. This helps with the regeneration process. Phylum Charactersitics Radial symmetry Spiny skin Suction cup/tube feet Mouth located in the middle of their oral surface Most are able to regenerate parts of their body Water vascular system Eye spots: No true eyes True coelom No head Evolutionary History of the Phylum Echinodermata It is believed that chorodates and echinodersms share a common ancestor, ancient deuterstormes. Ancestral Deuterostomes Phylum Echinodermata Phylum Chordata Class Holothruroidea Class Echinoidea Class Ophiuroidea Class Crinoidea Class Asteroidea Subphylum Vertebrata Subphylum Cephalochordata Subphylum Urochordata Example: Vertebrates Example: Lancelets Example: Tunicates Example: Sea Stars Example: Sea Lilies Example: Brittle Stars Example: Sea Urchins Example: Sea Cucumbers -Hermaphrodite- It matures as a male at about two years old before entering the female stage two years later.
-They are scavengers that feed on dead plants and animals.
-They can be olive green to pale orange.
-Live all over the rocky shore and under rocks in rockpools.
-A female can lay up to 1,000 orange eggs which hatch into baby cushion stars.
-Have a five-part radial symmetry
-Tube feet 'Aristole's Lantern- Urchins
-A structure that scrapes algea from rocks. Vacuum- Sea cucumbers
-They eat sand to extract food particles and then clean sand comes our of the other end. Stomach- Sea stars push their stomach out to the food instead of sending the food to their stomach. Brittle Stars feed by using their arms to capture food or by pushing mud containing food particles into their mouth. Questions: Sea stars are able to __________ arms and sometimes a new sea star.
Echinodermata comes from the Greek meaning _____________ How Organisisms in Echinodermata Circulate Nutrients Circulate water through their bodies, not blood. Their water vascular system not only transports molecules, but also works with muscles to move and walk. Open circulatory system How Organisms in Echinodermata Exchange Gases Asteroids and crinoids use thin layers of their epidermis, called dermal gills or papulae, for gas exchange. Urchins use many infoldings of the body wall opening outside by slits, and ventilated with cilia or muscular action. Sand dollars use highly modified podia on their aboral surface, which are flaplike and thin-walled. Holothurians use a highly branched hindgut called the "respiratory tree" for gas exchange, with water drawn in and released from the anus. How Organisms in Echinodermata Excrete Wastes How Organisms in Echinodermata Reproduce Ameboid cells carry wastes out of their body. Most excrete wastes through their anus. Brittle stars excrete wastes through their mouths. Most reproduce sexually, although most can reproduce asexually. In sexual reproduction, fertilization is usually external, but eggs may be brooded on or in the body. In asexual reproduction, regeneration occurs. How Organisms in Echinodermata Respond to the Environment: Nervous System Nerve ring that surrounds the mouth and coordinates their responses and movements. Sensitive to touch and changes in light intesity. -Many sea stars are top predators.
-A crown-of-thorns sea star may consume up to six square meters of living reef per year.
-Prevent the growth of a layer of filamentous aglae on coral reefs which can block constitutent organisms. Mouth Questions: Sea stars are able to REGENERATE arms and sometimes a new sea star.
Echinodermata comes from the Greek meaning SPINY SKIN. -Scientists are studying the crown-of-thorns sea star because every few years there is an outbreak in coral reefs near Australia.
-The SeaStar Foundation is dedicated to better understanding marine life as well as protecting it. The do research to enhance their understanding of such things.
-The Shed Aquarium was interested in opening a new exhibit and what they ended with was titled, 'Sea Star Quest'. Echinoderms in general were researched, but the sea star was the main species. This exhibit assesed how well people knew the phylum echiondermata, but for them to get all this knowledge they asked a group of people to research and then create this exhibit. Sea star feeding
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