What is the symmetry of mollusks?

What is the symmetry of mollusks?

Mollusks have bilateral symmetry.

Are molluscs bilaterally symmetrical?

Mollusks are generally considered a phylum of bilaterally symmetrical animals, although there are also many asymmetrical species.

What kind of symmetry does a clam have?

Bilateral symmetry

Is a scallop a Brachiopod?

The most common seashells at the beach today are bivalves: clams, oysters, scallops, and mussels. Bivalves and brachiopods are both sessile filter feeders, sitting on the seafloor and filtering water for food and oxygen. …

Is a starfish radially symmetrical?

No head, no tail, all arms –sea stars are just that: stars. Based on five-part radial symmetry (though some sea stars have many more arms), key functions are coordinated in the center of their bodies, then passed down the arms.

Do starfish have fingers?

Like fish gills, papulae absorb the oxygen in seawater. Such fleshy little fingers would make an excellent snack for a passing shrimp or another small predator. To defend themselves, starfish can retract their papulae to make them less obvious targets, as this Mithrodia clavigera, pictured below, has done.

What do echinoderms have instead of a brain?

Instead of a brain, echinoderms have a ring of nerves located around their mouth area that governs their nervous responses. This ring coordinates their motion, their eating, basically anything that requires nerve control.

Do echinoderms have brains?

Echinoderms have a simple radial nervous system that consists of a modified nerve net consisting of interconnecting neurons with no central brain, although some do possess ganglia.

Do sea cucumbers have a head?

Conversely, sea cucumbers have no definitive head end—they kind of look like underwater sausages. You can sometimes see tentacles coming out of one end that the cucumber uses to feed, but they can retract those back into their bodies.

Why are there no freshwater echinoderms?

Echinoderms are called “isotonic with their environment”. This means that the concentration of salts in their body is equal to the concentration of salts of the sea water in which they live. This is one of the most compelling reasons as to why there are no echinoderms in fresh water.

Is Starfish really a fish?

Sea stars, commonly called, “starfish,” are not fish. They do not have gills, scales, or fins. Sea stars live only in saltwater. Sea water, instead of blood, is actually used to pump nutrients through their bodies via a ‘water vascular system. Tube feet also help sea stars hold their prey.

Can starfish live in freshwater tanks?

Some starfish will survive in an aquarium if fed bits of clam, shrimp or other meaty fares, even though this might not be their natural diet. Many species can grow to quite a large size, which can cause a problem with them disrupting other tank life as well as possibly toppling or rearranging live rocks and corals.

Do echinoderms live in freshwater?

Echinoderms are the largest phylum with no freshwater or terrestrial forms. Echinoderm environments must be marine, as in saltwater, for the echinoderm to survive. Within marine environments, the conditions echinoderms live in can vary greatly.