Final answer:
Invertebrates with soft bodies that are often covered by a shell are called mollusks, which belong to the Phylum Mollusca. These organisms typically have a muscular foot, a visceral mass, a mantle, and often have a hard external shell composed of calcium carbonate, although this shell can be reduced or absent in some species like squids and octopuses.
Step-by-step explanation:
Invertebrates with Soft Bodies and Shells
Invertebrates that typically have soft bodies and are often covered by a shell are known as mollusks. These creatures fall under the Phylum Mollusca, which includes various species such as snails, slugs, oysters, clams, and octopuses. Mollusks are incredibly diverse in form, but they commonly possess a muscular foot used for movement, a visceral mass containing their internal organs, and a mantle which secretes their hard shell made of calcium carbonate, although the presence and size of this shell can vary.
While many mollusks have a hard external shell, some like the squid and octopus only have a reduced internal shell or none at all. However, these mollusks still maintain other characteristic features such as the mantle and the radula, an abrasive tonguelike structure for feeding. The majority of mollusks inhabit marine environments, although several can also be found in freshwater and terrestrial habitats.
Members of the Phylum Mollusca are part of a larger group called Lophotrochozoa, and they are distinct from other invertebrate groups such as the Ecdysozoa, which includes nematodes and arthropods.