External Anatomy Of Starfish

Starfish are deuterostome animals like the chordates. Water vascular system 9.

Starfish Aboral Surface Diagram Wiring Diagram Images Gallery

Some sea stars like the crown of thorns starfish have large spines.

External anatomy of starfish. Habit and habitat of asterias 3. Sea stars are invertebrates and organisms with no head but tube feet and arms where they can sense as well as see. In this article we will discuss about asterias starfish 1.

Most species have five arms or rays radiating from a central disk although several species have six or more arms. Ventral view of starfish showing external anatomy. Most starfish have five arms however some have more or less.

History of asterias 2. Others eg blood stars have spines so small that their skin appears smooth. Start studying starfish anatomy externalinternal.

In fact some starfish can have different numbers of arms even within one species. They have radial symmetry and an oral surface as well as aboral with the arms and disk covered with spikes. Dorsal view of a dissected starfish showing gonads and ampullae.

Dorsal view of a dissected starfish showing pyloric cecum and pyloric ducts. Place the starfish on your dissection tray with its aboral surface facing upward. Close up of madreporite and stone canal.

Others eg blood stars have spines so small that their skin appears smooth. These five arms or more can regenerate them as long as the central disk is not affected. Respiratory and excretory system 12.

External anatomy starfish express pentamerism that is pentaradial symmetry. Learn vocabulary terms and more with flashcards games and other study tools. Asteris arm microscopic xs.

These are the five extensions that you see projecting from the middle of the starfish. Arms or rays. Using your diagram sheets and the pictures below to locate the following structures and note their functions.

Sea stars are composed of a central disc from which arms sprout in radial symmetry. Dissection showing where cardiac stomach opens into the mouth. A 2014 analysis of 219 genes from all classes of echinoderms gives the following phylogenetic tree.

The times at which the clades diverged is shown under the labels in millions of years ago mya.

Starfish Wikipedia