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Which mollusks have an internal shell?

Which mollusks have an internal shell?

Cuttlefish, squid, spirula, vampire squid, and cirrate octopuses have small internal shells.

In which molluscs is the shell absent?

Class Aplacophora (“bearing no plates”) includes worm-like animals primarily found in benthic marine habitats. These animals lack a calcareous shell but possess aragonite spicules on their epidermis. They have a rudimentary mantle cavity and lack eyes, tentacles, and nephridia (excretory organs).

Do mollusks have an internal or external shell?

Mollusks have a hard outer shell. There is a layer of tissue called the mantle between the shell and the body. Most mollusks have tentacles for feeding and sensing, and many have a muscular foot. Mollusks also have a coelom, a complete digestive system, and specialized organs for excretion.

What mollusk has completely lost their shell?

In many aspects of their anatomy and behaviour, the most advanced cephalopods are the octopods (Octopus and its relatives), and in this group the shell has been lost completely.

What are 4 examples of mollusks that do not have shells?

Mollusks without shells include squid, banana slugs, and octopi. Some mollusks are terrestrial, occurring in most environments on earth, while others live in the water for some or all of their life.

How is the blood flow inside a clam’s body different from the blood flow inside of your body?

Clams have an open circulatory system; humans have a closed circulatory system. The open system of the clam is not complete; blood pools around the heart, as a result there is less pressure. The blood of the closed system like humans is confined within the blood vessels and heart, resulting in a high pressured system.

Which one grows over molluscan shell?

Protoderma.

What type of mollusks do humans eat?

Edible molluscs are harvested from saltwater, freshwater, and the land, and include numerous members of the classes Gastropoda (snails), Bivalvia (clams, scallops, oysters etc.), Cephalopoda (octopus and squid), and Polyplacophora (chitons).

What type of mollusk is considered to be the smartest?

The cephalopod class of mollusks are considered the most intelligent invertebrates and an important example of advanced cognitive evolution amongst animals in general.

What are three examples of bivalves?

Clams, oysters, scallops, and mussels are bivalves. This type of mollusk does not have a radula.

What are the 4 major groups of living mollusks?

The major classes of living mollusks include gastropods, bivalves, and cephalopods (Figure below).

  • Gastropods. Gastropods include snails and slugs. They use their foot to crawl.
  • Bivalves. Bivalves include clams, scallops, oysters, and mussels.
  • Cephalopods. Cephalopods include the octopus and squid.

What could be the advantage of a reduced internal shell?

“By having a reduced internal skeleton compared to their ancient relatives, the modern squids and octopuses could compress their body and more efficiently jet away leaving a baffling cloud of ink with the attacking predator.