Classes
Class Asteroidea aka "Asteroids"
This class contains arguably the most well known echinoderm of them all, the sea star and there are about 1,500 species. Asteroids in this class are mostly 12-24 cm in size, but some are less than 2 cm and some are more than a meter. They can be found in the Arctic Ocean, Indian Ocean, Atlantic Ocean, Pacific Ocean, and Mediterranean Sea. The water-vascular system of an asteroid begins at the madreporite, which is located near the center of its body. Through the madreporite leads into the stone canal which is attached to the ring canal and leads to the radial canals. The canals end at the tube foot, each tube foot is made of an ampulla, a podium, and, sometimes, a sucker. The oral surface of an asteroid is where the mouth is located. The hemal system is parallel to the water-vascular system and helps distribute nutrients to the asteroid.
Asteroids are capable of regenerating lost limbs, albeit it can take quite some time for the arm(s) to fully regenerate. Some are even able to reproduce asexually through regeneration. Asteroids have their own sexes but some are hermaphroditic. Externally, male and female asteroids look identical. Usually, a pair of gonads are in each arm.
Since asteroids are very slow, their diet consists of other creatures that are just as slow as them. These include gastropods, bivalves, barnacles, and other invertebrates.
Source: http://animaldiversity.ummz.umich.edu/accounts/Asteroidea/
Edmodo notes
This class contains arguably the most well known echinoderm of them all, the sea star and there are about 1,500 species. Asteroids in this class are mostly 12-24 cm in size, but some are less than 2 cm and some are more than a meter. They can be found in the Arctic Ocean, Indian Ocean, Atlantic Ocean, Pacific Ocean, and Mediterranean Sea. The water-vascular system of an asteroid begins at the madreporite, which is located near the center of its body. Through the madreporite leads into the stone canal which is attached to the ring canal and leads to the radial canals. The canals end at the tube foot, each tube foot is made of an ampulla, a podium, and, sometimes, a sucker. The oral surface of an asteroid is where the mouth is located. The hemal system is parallel to the water-vascular system and helps distribute nutrients to the asteroid.
Asteroids are capable of regenerating lost limbs, albeit it can take quite some time for the arm(s) to fully regenerate. Some are even able to reproduce asexually through regeneration. Asteroids have their own sexes but some are hermaphroditic. Externally, male and female asteroids look identical. Usually, a pair of gonads are in each arm.
Since asteroids are very slow, their diet consists of other creatures that are just as slow as them. These include gastropods, bivalves, barnacles, and other invertebrates.
Source: http://animaldiversity.ummz.umich.edu/accounts/Asteroidea/
Edmodo notes
Class Crinoidea
Class Crinoidea contains about 600 species and includes the sea lilies and the feather stars. Many of them reside in the deep sea, but some can be found in shallow coral reefs. The calyx is one of the main body regions of a crinoid, it is the cup-shaped part of a crinoid's body. Most of the organs are inside of the calyx. The mouth and the anus open up on the oral surface. The "stalk" of a sea lily is permanently attached to a surface, but feather stars lack a stalk and can move by moving their rays up and down. The unattached end of a crinoid is called the "crown". All crinoids filter feed and the tube feet are used to help move food towards the mouth. The entire digestive system of a crinoid is found in the calyx. Their digestive system is basically nothing more than a mouth and an intestine. The gonads are located in the rays.
The nerves of a crinoid can be found throughout their body, but regeneration seems to mostly take place in the calyx. There is an estimated 5,000 fossil species of crinoids, the greatest diversity of crinoids was during the Paleozoic era.
Source: http://animaldiversity.ummz.umich.edu/accounts/Crinoidea/
Edmodo notes
Class Crinoidea contains about 600 species and includes the sea lilies and the feather stars. Many of them reside in the deep sea, but some can be found in shallow coral reefs. The calyx is one of the main body regions of a crinoid, it is the cup-shaped part of a crinoid's body. Most of the organs are inside of the calyx. The mouth and the anus open up on the oral surface. The "stalk" of a sea lily is permanently attached to a surface, but feather stars lack a stalk and can move by moving their rays up and down. The unattached end of a crinoid is called the "crown". All crinoids filter feed and the tube feet are used to help move food towards the mouth. The entire digestive system of a crinoid is found in the calyx. Their digestive system is basically nothing more than a mouth and an intestine. The gonads are located in the rays.
The nerves of a crinoid can be found throughout their body, but regeneration seems to mostly take place in the calyx. There is an estimated 5,000 fossil species of crinoids, the greatest diversity of crinoids was during the Paleozoic era.
Source: http://animaldiversity.ummz.umich.edu/accounts/Crinoidea/
Edmodo notes
Class Echinoidea
There about 1,000 species in class echinoidea and they are home to the sea urchins and sand dollars. This class of species are specialized to live on rough surfaces and can live in depths as deep as 5,000 meters. They have a test which consists of 10 plates. Five of them are ambulacral plates, the tube feet and five interambulacral plates, the spines. The spines and tube feet are used for moving, burrowing, and gathering food. For the most part, urchins have longer spines and sand dollars have shorter spines which gives them a fuzzy appearance. The spines of some species of echinoids contain venom. To move, they push against the surface using their spines. Their water-vascular system and nervous system is similar to that of other echinoderms. Echinoids aren't picky eaters and will eat just about anything edible they come across, which can be algae, kelp, coral, and dead animals. As a result of their eating habits, large groups of sea urchins are capable of completely ravaging and devouring forests of kelp in just a few days.
Source: http://animaldiversity.ummz.umich.edu/accounts/Echinoidea/
Edmodo notes
There about 1,000 species in class echinoidea and they are home to the sea urchins and sand dollars. This class of species are specialized to live on rough surfaces and can live in depths as deep as 5,000 meters. They have a test which consists of 10 plates. Five of them are ambulacral plates, the tube feet and five interambulacral plates, the spines. The spines and tube feet are used for moving, burrowing, and gathering food. For the most part, urchins have longer spines and sand dollars have shorter spines which gives them a fuzzy appearance. The spines of some species of echinoids contain venom. To move, they push against the surface using their spines. Their water-vascular system and nervous system is similar to that of other echinoderms. Echinoids aren't picky eaters and will eat just about anything edible they come across, which can be algae, kelp, coral, and dead animals. As a result of their eating habits, large groups of sea urchins are capable of completely ravaging and devouring forests of kelp in just a few days.
Source: http://animaldiversity.ummz.umich.edu/accounts/Echinoidea/
Edmodo notes
Class Holothuroidea
This class contains about 1,100 species of holothourions aka sea cucumbers. They can be found in shallow waters as well as deep ocean floors. They can be located in the Indian Ocean, Pacific Ocean, Atlantic Ocean, and Mediterranean Sea. Most holothourions are black, brown, or olive green in color. Their bodies are elongated which gives them an appearance similar to that of worms. Some holothourions are round in shape. Tube feet surround their mouths and are enlarged and modified, they are given the label "tentacles". They lack spines and pincers on their skin. Their madreporite is internal, rather than external, which means they use their own body fluids rather than water. The ring canal encircles their esophagus. Five radial canals and five rows of ampullae and tube feet line their bodies.
They are very slow and eat food by sweeping their tentacles along the ocean floor. The tentacles trap the sand and any organic matter that was picked up is digested and the sand is extracted. Holothourions use a "respiratory tree" to breathe. Some are capable of shooting tubules out of this tree for defense.
Source: http://animaldiversity.ummz.umich.edu/accounts/Holothuroidea/
Edmodo notes
This class contains about 1,100 species of holothourions aka sea cucumbers. They can be found in shallow waters as well as deep ocean floors. They can be located in the Indian Ocean, Pacific Ocean, Atlantic Ocean, and Mediterranean Sea. Most holothourions are black, brown, or olive green in color. Their bodies are elongated which gives them an appearance similar to that of worms. Some holothourions are round in shape. Tube feet surround their mouths and are enlarged and modified, they are given the label "tentacles". They lack spines and pincers on their skin. Their madreporite is internal, rather than external, which means they use their own body fluids rather than water. The ring canal encircles their esophagus. Five radial canals and five rows of ampullae and tube feet line their bodies.
They are very slow and eat food by sweeping their tentacles along the ocean floor. The tentacles trap the sand and any organic matter that was picked up is digested and the sand is extracted. Holothourions use a "respiratory tree" to breathe. Some are capable of shooting tubules out of this tree for defense.
Source: http://animaldiversity.ummz.umich.edu/accounts/Holothuroidea/
Edmodo notes
Class Ophiuroidea
Ophiuroidea contains about 2,000 species and are the most diverse group of echinoderms. Brittle stars and basket stars are two well known members of this group. Their arms are long and sharply set off from the central disk. Brittle stars have non-branching arms and basket stars have branching arms. Their tube feet lack suction cups and ampullae. Ophiuroids are capable of regeneration, but if every arm is cut off from the central disk, the ophiuroid will die. Their water-vascular system is used for moving. Some ophiuroids lack a madreporite, a radial canal extends into each arm and lateral canals supply the tube feet.
Ophiuroids are carnivores, scavengers, or filter feeders. Some species use more than one method to get food. Brittle stars hunt for food and basket stars are suspension feeders. Ophiuroids are dioecious, the males are smaller than the females.
Source: http://animaldiversity.ummz.umich.edu/accounts/Ophiuroidea/
Edmodo notes
Ophiuroidea contains about 2,000 species and are the most diverse group of echinoderms. Brittle stars and basket stars are two well known members of this group. Their arms are long and sharply set off from the central disk. Brittle stars have non-branching arms and basket stars have branching arms. Their tube feet lack suction cups and ampullae. Ophiuroids are capable of regeneration, but if every arm is cut off from the central disk, the ophiuroid will die. Their water-vascular system is used for moving. Some ophiuroids lack a madreporite, a radial canal extends into each arm and lateral canals supply the tube feet.
Ophiuroids are carnivores, scavengers, or filter feeders. Some species use more than one method to get food. Brittle stars hunt for food and basket stars are suspension feeders. Ophiuroids are dioecious, the males are smaller than the females.
Source: http://animaldiversity.ummz.umich.edu/accounts/Ophiuroidea/
Edmodo notes
Representative Organism: Mediaster Aequalis
- Class: Asteroidea
- Common name: Vermilion star, Red sea star
- Scientific name: Mediaster aequalis
- Can be red and orange in color
- One of the smaller sea stars
- Can be found in Chignik Bay, and Alaska to Baja California
- Their depth range is anywhere from inter-tidal to 500 meters
- Their habitat varies
- Their diet consists of sponges, bryozoans, sea pens, algae, etc.
Source: http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Echinodermata/Class%20Asteroidea/Mediaster_aequalis.html