Asked by: Amanda Torres
Clams lack cephalization because in the nervous system, there are three pairs of ganglia. A clam is a filter feeder which the food and water enter incurrent siphon, mucous secretions maintain food to gills and mouth, anus empties into excurrent siphon.
Are all molluscs cephalized?
Both molluscs and annelids probably evolved from free-living flatworms. Both flatworms and molluscs are triploblastic, bilaterally symmetric, and cephalized. But molluscs have developed a true coelom, an internal body cavity enclosed by mesodermal membranes.
Do clams have a head?
Clams burrow by means of a muscular foot, located at the front end, which can be extruded between the valves. The head, located within the shell, is rudimentary, without eyes or antennae.
Are bivalves cephalized?
For example, bivalves are not particularly cephalized (although some scientists have argued that they are “all head”). However, as with the echinoderms, certain mollusks regained cephalization.
What do clams use to move?
How do clams move? Clams have the most control of their movement using their foot. This foot allows for a certain amount of lateral (side-to-side) movement. However, this foot is most useful for allowing the clam to burrow into the sand.
What is clam cephalization?
Animals with bilateral symmetry also usually have a distinct head at one end, with a mouth and sense organs. We say they are cephalized, meaning “head-having” [“SEFF-alized”]. In contrast, animals with radial symmetry are not cephalized: They have no head, just a mouth in the middle.
Do bivalves show cephalization in clams?
Bivalve means “two shells.” The animals of this phylum have a hinged, two-part shell and include clams, oysters, scallops, and mussels. Bivalves are a bit of an exception to the cephalization that characterizes most mollusks. Bivalves don’t have a head. They feed by filtering out food from the water in which they live.
Do clams have vision?
Giant clam vision
They observe the world through several hundred tiny pinhole eyes along the edge of their soft bodies. Pinhole eyes are the shape of a deep cup and have a narrow opening, but no lens.
Do clams feel pain?
Yes. Scientists have proved beyond a doubt that fish, lobsters, crabs, and other sea dwellers feel pain. Lobsters’ bodies are covered with chemoreceptors so they are very sensitive to their environments.
Are clams blind?
Usually clams do not have heads, and they are blind without eyes, but Scallops have eyes.
Do clams have consciousness?
Clams can feel certain sensations and respond, but there’s almost certainly no conscious thought. Clams aren’t planning for the future or thinking about what to do next, they just drift around and react to stimulus while performing instinctual tasks.
Can a clam walk?
Both male and female clams were observed walking and they tended to walk towards members of the opposite sex. In the walking areas, clams were more aggregated.
How do clams anchor themselves in the sand?
Braced in the sand, the clam thrusts its fleshy foot downward. Then it squeezes water into the bottom of its foot, causing the appendage to balloon. So anchored, the clam contracts. The pocket of sand around the clam “fluidizes,” loosening up and reducing the drag on the clam, so the shell can slide down to the foot.
How do clams open and close their shells?
Clams close their shells with powerful adductor muscles which pull the two valves together. A springy ligament at the hinge pulls the shell open when the muscles relax. Just like us, the clam needs to use nerve cells to signal the muscle to do its thing.
How do clams breathe when buried in the sand?
To protect themselves clams burrow down in the mud and sand using their foot. They can burrow more than 11 inches! When the tide comes in, they stick their siphons out and inhale fresh seawater to get oxygen so they can breathe.