Phylum Echinodermata

Phylum Echinodermata By Kayla Wilkinson

Class Asteroidea • Sea stars • Most have 5 rays • Some may have more • Rays are tapered and extended from the central disk • Have an endoskeleton • Water flows in and out the water vascular system through the madreporite

Class Asteroidea • Have tube feet • Have eyespots at the end of each ray • To eat sea stars push their stomachs out their mouth and spread their mouth over their food • Then enzymes turn the solid food into a liquid • The stomach then pulls back into the body

Class Asteroidea • They excrete waste out the anus • Have pincer like pedicellariae that will pinch any animal that tries to crawl over it

Class Ophiuroidea • Brittle stars • Extremely fragile • If you pick one up some of its rays will fall off • This is their way of escape • While the predator is messing with the broken off ray the brittle star can escape • A new ray will regenerate within weeks

Class Ophiuroidea • Don’t use tube feet for locomotion • Propel themselves with the snake-like, slithering motion of their flexible rays • Use tube feet to pass food particles up the rays and into the mouth

Class Echinoidea • Sea urchins and sand dollars • Globe- or disk-shaped animals covered with spines • Don’t have rays • Sand dollars have a five-petaled flower pattern on the surface • Sand dollars covered with tiny, hair-like spines that are shed when the animal dies

Class Echinoidea • Sand dollars have tube feet that come out of the petal-like marking of the upper surface • They are modified into gills • Tube feet on bottom used for bringing food particles to the mouth

Class Echinoidea • Sea urchins look like pincushions • Long usually pointed spines • Have long slender tube feet that aid in locomotion • Spines protect from predators • Also aid in locomotion such as burrowing

Class Holothuroidea • Sea cucumbers • Leathery covering that allows them to be more flexible than any other echinoderms • Move with tentacles and tube feet • When threatened they will rupture their internal organs and release them out their anus • Then regenerate them within a few weeks

Class Holothuroidea • This confuses predators and the sea cucumber can get away • Reproduce by shedding eggs and sperm into waterwhere fertilization takes place

Class Crinoidea • Sea lilies and feather stars • Resemble plants • Sea lilies only sessile echinoderms • Feather stars are sessile during larval form only • Adult feather stars use feathery arms to swim from place to place • Use feathery rays to capture organic particles

Phylum Echinodermata