Echinoderms Flashcards
How many species of Echinoderms are there?
6000
Name the 5 classes of Echinoderm
Crinodea - feather stars and sea lilies Ophiuroidea - brittle stars and basket stars Asteroidea - starfish Echinodea - sea urchins and sand dollars Holothuroidea - sea cucumbers
What is the ecological importance of Echinoderms?
Important grazers, sediment feeders and predators
What are pedicillerae?
Small wrench/claw shaped structures seen on the body surface - their true function is unknown yet scientists believe they perhaps clean the body surface of encrusting organisms, they are sometimes used for prey capture
How to starfish move?
Water-vascular system alternates hydrostatic pressure in chambers called ampullae, extending tube feet with suckers that extend and drag the starfish along the sea floor
Where are most of a starfishes sensory neurones?
End of feet
What is a madeporite?
A sieve like structure regulating the WVS pressure by allowing the entry of seawater into the stone canal which connects to the ring canal around the mouth
Describe a starfishes ‘skeleton’
They have a calcitic skeleton composed of tiny ossicles. Embryologically they form a true endoskeleton but mechanically, they act as an exoskeleton. The ossicles are connected by collaged ligaments which can be locked and unlocked, allowing echinoderms to retain a variety of postures with zero muscular effort
Can echinoderms osmoregulate?
No. They are all marine
Name the two types of Hemichordates
Acorn worms and Sea angels
Describe Acorn worms
Soliary - live in burrows
They are slow burrowers, and use their proboscis to deposit feed or filter feed
Describe Sea angels
Sessile, anus is near mouth
Zooids protract their food gathering ring of tentacles
Asexual reproduction by budding
