echinoderms

bio 2.2 zoology

Are sea stars bilaterally or radially symmetrical?

They are both, their larvae are bilaterally symmetrical and as adults they are radially symmetrical

why are their nervous system decentralized?

They experience their environment from 360 degrees.

How do they experience their enviornment?

they have eyespots on their arms and have chemoreceptors

osmoconformers

maintaining the osmotic pressure of their environment 

what is their endoskeleton made of?

Calcium carbonate

what makes the echinoderms unique?

water-vascular system

How do they move around

they have tube feet which help them move around and catch prey.

what are the five classes of echinoderms?

Asteroidea, Ophiuroidea, Echinoidea, Holothuroidea, Crinoidea 

Asteroidea

the sea star

ophiuroidea

brittle stars

echinoidea

the sand dollars and sea urchins

holothuroidea

the sea cucumbers

Crinoidea

sea lilies and feather stars

endoskeleton

made of calcareous plates fused together beneath their epidermis

dermal ossicles

calcareous plates

what makes the sea stars skeleton so unique

Their collagen can harden and soften as needed for the sea star to take a new shape.

How do they breath

via papulae

how do sea stars protect themselves?

skeletal spines that stick out.

which echinoderm does not have a well defined skeleton?

sea pickles they reduced their dermal ossicles to a point where it feels as soft as a squid

pedicellareae

tiny calcareous pincers

which classes have pedicellareae

echinoids and asteroids

Papulae

pouches in the coelomic cavity that extend through gaps in the derma ossicles. Helps diffuse waste

Madreporite

inlet for water which runs the water vascular system, Only on two arms

Sensory tentacles

photoreceptors and statocysts at the end of each arms 

pyloric cecae

yellowish-brown digestive glands

Where can you find the gonads?

underneath the pyloric cecae

ampulla

tops of the tube feet

What does the stone canal do?

takes water to the ring canal and out to the radial canals which run down each arm

lateral canals

they have one way valves the branch off the radial canal and fill the ampullae with water

label the spines and pedicellareae

what is the circled part called?

ring canal 

label: ampulla, digestive gland, gonads, and radial canal

label the crossed out sections

stone canal and madreporite