Marine Biology - Phylum Echinodermata

Examples of Echinoderms

Sea Stars and brittle stars, sea lilies, feather stars, sea urchins, sea cucumbers, and sea dollars

What does Echinoderm mean

Spiny Skin

What characteristics do Echinoderms share?

Spiny skin, Endoskeleton, Five part body-pentaradial symmetry, Water vascular system, Tube feet, Sutotomy (regeneration)

What are two ways Echinoderms spines can look like?

Small hair-like spines (starfish) or Long spines (sea urchin)

What is the internal skeleton of an Echinoderm called?

Ossicles (bony plates)

Define Brittle / Sea Stars ossicles

Many small plates that move with one another

What is the ‘test’

Skeleton plates fused into a shape (Sea Urchin and Sand Dollar)

What Echinoderm had its ossicles degenerated and buried in a leathery body?

Sea Cucumber

What is the water vascular system?

a system of tubes that carry food and oxygen and remove wastes.

Describe what happens in the WVS

Water enters madreporite on aboral surface into a short, straight stone canal. Stone canal connects to circular canal around the ring canal. Enters five radial canals extending down each arm

What are tube feet used for?

Moving and getting food

What do each of a sea star's canals end in?

Tube feet.

What causes a sea star’s tube feet to extend or contract?

Varying internal water pressure changes the shape of the ampulla (bulb-like sacs).

Where is the mouth of a sea star located?

On the oral surface (bottom/ventral side).

Where is the anus of a sea star located?

On the aboral surface (top/dorsal side).

What do sea stars often prey on?

Bivalves and coral.

How do sea stars eat?

Pop stomach out mouth

What body part do sea stars have that can regenerate if lost?

Arms

How many rows of tube feet are typically on each ray of a sea star?

2 to 4 rows extend from ambulacral groove

What is pedicellariae?

tiny, forcep-like structures on aboral surface to pick up & remove dirt

What organ systems do sea stars lack?

No circulatory, excretory, or respiratory systems,head or brain

Where are the eyespots on a sea star?

Tips of each arm, can detect light

What type of reproduction do sea stars have?

Separate sexes with external fertilization.

How many eggs can a female sea star produce in one season?

About 200,000,000 eggs

What is unique about the movement of brittle stars?

They have fast, snake-like movement and are the most mobile echinoderms.

What is the typical diet of brittle stars?

They are scavengers.

What happens if a brittle star's arm is grabbed by a predator?

The arm breaks off readily to escape.

What class are brittle stars in?

The largest class of echinoderms (includes basket stars).

What type of body do sea cucumbers have?

Lack arms & visible spines, Elongated, Flexible, leathery body

How do sea cucumbers feed?

Using sticky tentacles to trap plankton or eating detritus.

Where do sea cucumbers breathe from?

Anus

What is evisceration

Eject internal organs to scare predators

What is the sea cucumber’s symbiotic relationship with the pearl fish?

Lives in its anus. Feed on gonads by day

What do sea urchins use their spines for?

Protection, capturing food, and movement.

What kind of spines do some sea urchins have?

Poisonous spines

Where is a sea urchin's mouth located?

Hidden under its body

What is aristotle’s lantern?

5 teeth together like bird’s beak; to scrape algae from rocks

How are sand dollars related to sea urchins?

They are the flattened versions of sea urchins

Where do sand dollars live?

in sand along coastlines

How do sand dollars get food to their mouths?

Food falls between dense spines and is carried by cilia and tube feet.

What do sand dollars use their spines for?

Burrowing

How are sea biscuits different from sand dollars?

They are not flat

Where do sea biscuits live and how do they move?

In sand along coastlines; they burrow using short, dense spines

What do sea biscuits use their tube feet for?

Respiration

What do sea biscuits eat?

Detritus in the sand.

What do sea lilies and feather stars eat?

They are filter feeders

Are sea lilies and feather stars mobile?

Yes, they can detach and move around.