Phylum Echinodermata By: Anna Grace Watkins

Ehinoderm Characteristics: Approximately 6,000 species. Moves by means of hundreds of hydraulic , suction cup-tipped

appendages and have skin covered with tiny, jaw-like pinchers. Echinoderms are found in all the oceans of the world. They have endoskeletons. They have long, tapering arms that are called rays. They are also radial symmetrical. Also have a simple nervous system. They have no head or brain, but do have a central nerve ring that

surrounds the mouth. They have cells that detect light and touch, but most do not have sensory

oragns. Echinoderms have a water vascular system that enables them to:

› Move› Exchange Gases› Capture food › Excrete Wastes

Class Asteroidea: More than 1/3 of the 6,000 species of Echinoderms belong to this

phylum. Sea stars belong to this class. Endoskeleton Pedicellariae Madreporite Tube Feet Anus Stomach Tube Feet Eyespots Most have 5 rays, but some have more.

› Some even have more than 40 rays.

Sea Star Pictures:

Class Ophiuroidea: “Brittle Stars” They are extremely fragile. Brittle Stars do not use their tube feet for

locomotion, but instead they use them to propel themselves with the snakelike, slithering motion.

Their body parts break easily but grow back with regeneration.

They also use them to pass particles of food along rays and into the mouth in the central disk.› This adaptation is an advantage because it helps them

survive attacks by keeping the predator busy with the broken piece.

Brittle Star Pictures:

Class Crinoidea: “Sea Lilies & Feather Stars” They resemble plants in some ways. Sea Lilies are the only sessile

echinoderms. Feather stars are sessile only in larval

form. They use their feathery rays to capture

downward drifting organic particles.

Sea Lilies & Feather Star Pictures:

Class Holothuroidea: “Sea Cucumber” Vegetable-like appearance! They reproduce by shedding eggs and sperm into the

water, where fertilization occurs! They have a leathery covering that allows them to be more

flexible than others. When harmed they may: expel a tangled, sticky mass of

tubes through the anus, or release some internal organs that are regenerated in a few weeks.

These really confuse their predators so therefore they can make a quick escape. They trap organic particles by sweeping their mucus-covered tentacles over the ocean bottom.

Sea Cucumbers Pictures:

Class Echinoidea: “Sea Urchins & Sand Dollars” Globe- or disk-shaped animals covered pointed

spines. Its spine protects it from predators. They have long, slender tube feet that, along with

the spines, aid the animal in locomotion. The spines also aid in locomotion and in burrowing. Sea Urchins often burrow into rocks to protect

themselves from predators and rough water. Sand dollars burrow into the sandy ocean bottom. They feed on tiny organic particles found in the

sand.

Sea Urchins & Sand Dollar Pictures:

The End!