Starfish Dissection Phylum Echinodermata ABORAL VIEW TOP OF

Starfish Dissection Phylum: Echinodermata

ABORAL VIEW “TOP OF THE STARFISH” Starfish usually have five legs or rays. If a leg gets cut off they can replace it by regeneration. In the middle of the arms or rays is the central disk. The madreporite is used to absorb water for the water vascular system. The water vascular system is a network of canals that the starfish uses for movement. A starfish’s skin is covered with spines or pedicellaries. The anus is on the top of the starfish which is opposite of most animals.

or arm or pedicellaries Anus

1. Look at diagram #1 on the activity sheet. 2. Label the structures on the lines that have a number. 3. When you are finished, proceed to the next slide.

ORAL VIEW “BOTTOM OF STARFISH” A starfishes mouth is located on the bottom. A starfish eats clams. Its tube feet are used to open a clam’s shell. Once the clam is open, the starfish turns its stomach inside out. The stomach comes out of its mouth and surrounds the clam, digests it, and then pulls its stomach back through its mouth.

1. Look at diagram #2 on the activity sheet. 2. Label the structures on the lines that have a number. 3. When you are finished, proceed to the next slide.

INTERNAL STRUCTURES Most of the inside of each arm or ray is filled with the hepatic caecum which is a digestive organ used to help digest food. The yellow colored structures are called gonads. These produce egg cells and sperm for sexual reproduction. Locate the ampullae. The tube feet are anchored to the arm or ray. The starfish has two stomachs: cardiac and pyloric stomachs.

1. Answer the questions on your activity sheet. 2. Feel free to go back and re-read the information presented in the slide show. 3. Turn in your activity sheet to the teacher. 4. Turn your computer off. 5. Place it in the computer cart and plug it in. 6. Get the early finisher activity from the teacher.