Unit 3 - Phylum Echinodermata

What is new about Phylum Echinodermata?

First time we see deuterostome development.

What are the 3 classes of Phylum Echinodermata?

Asteroidea - Sea Stars

Echinoidea - Sea urchins

Holothuroidea - Sea cucumbers

What is the importance of deuterostome development?

Humans and other vertebrate animals also have deuterostome development, which is why we are more closely related to sea stars than other invertebrates.

What is deuterostome development?

Blastopore develops into an anus, and the anus develops before the mouth.

What is the general structure of an Echinodermata?

Radial symmetry

Aboral side- anus

Oral side - mouth

What kind of symmetry do SOME Echinodermata have?

Pentaradial symmetry

What do sea stars eat, and how?

They eat bivalves, which are clams and oysters. They extend their stomachs out of their mouths to digest food.

What kind of organ systems are Echinodermatas missing?

Circulatory, Excretory, Respiratory systems.

What special system do Echinoderms rely on to accomplish the function of their missing systems?

They depend on water vascular system and simple diffusion.

How does the nervous system work in Echinodermata’s?

Central nerve ring and radial nerve, coordinates movement of the tube feet.

What happens if you chop a sea star into 2 pieces?

Both pieces regrow because they can reproduce asexually that way.

How do sea urchins defend itself against predators?

Some sea urchins can detach pedicellaria heads from their bodies like missiles, and the heads seek out and attacks the target.

How do sea stars defend itself against predators?

They can detach an arm as a sacrifice to escape.

How do sea cucumbers defend itself against predators?

They can push out their internal organs as a sacrifice, allowing them to escape.

What is the environmental role of sea stars?

They eat algae, which benefits corals.

What is the environmental role of sea urchins?

They are eaten by otters, which benefits kelp forests.

What is the environmental role of sea cucumbers?

They filter sediment, which benefits water quality.