Mollusks

Yeah

I think you mean when did they come into existence. All the major classes of mollusks (except scaphopods) [tusk shells] were established in the Cambrian.

Since there are fewer mollusks today than in the past, it appears that they have not been evolving at all, but simply going extinct. Both the genetics and the fossils agree with the Bible. Mollusks were expertly formed from the beginning and have not evolved since.

The Cambrian Period is the first geological time period of the Paleozoic Era (the "time of ancient life"). This period lasted about 53 million years and marked a dramatic burst of evolutionary changes in life on Earth, known as the "Cambrian Explosion."

Among the animals that evolved during this period were the chordates - animals with a dorsal nerve cord; hard-bodied brachiopods, which resembled clams; and arthropods - ancestors of spiders, insects and crustaceans.

The International Geological Congress places the lower boundary of the period at 543 million years ago with the first appearance in the fossil record of worms that made horizontal burrows. The end of the Cambrian Period is marked by evidence in the fossil record of a mass extinction event about 490 million years ago.

The period gets its name from Cambria, the Roman name for Wales, where Adam Sedgwick, one of the pioneers of geology, studied rock strata. Charles Darwin was one of his students. (Sedgwick, however, never accepted Darwin's theory of evolution and natural selection.)

Somewhere in that range of 543 to 490 years ago.

Other nudibranch's

actually,snakes are both oviparous and ovoviviparous...

A cephalopod

is any member of the molluscan

phylum Cephalopoda

(Greek plural Κεφαλόποδα

(kephalópoda);

"head-feet").

These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles (muscular hydrostats)

modified from the primitive molluscan

foot. Fishermen sometimes call them inkfish,

referring to their common ability to squirt ink. The study of cephalopods

is a branch of malacology

known

as teuthology

Yes, most clams are hermaphrodites, meaning they possess both male and female reproductive organs. This allows them to reproduce by both self-fertilization and cross-fertilization with other individuals.

It's located in the Philippines, i think it's name was pisidium

the bahamas

Cephalopods

have a trochophore

Chitons are organisms belonging to the class of Polyplacophora which in turn belonging to the phylum mollusca. They are mostly very small anymals (2 to 5 cm - 1 to 2 inches) with a week body, like other molluscs and attached to the surface with its food. Eight plates protect the soft body.

Sexes are separate; it means that sperm is produced by the male chitons and eggs are produced by the female chitons. Sperm is secreted by the males into the water. This sperm flows through the gills of the female and fertilize the eggs. Fertilized eggs are shed into the sea as separate eggs or as a jelly mass. Usually molluscs metamorphoses through two larval stages, i.e. a trochophore and a veliger larvae stadium. But a chiton skips the veliger stadium and metamorphoses from a trochophora larva to an adult.

a scorpion is a Arthropods

mollusks have a tube like foot that looks like a suckction cup

yes

Polyplacophora is a class of marine mollusks commonly known as chitons. They are characterized by their eight overlapping dorsal shells or plates, which provide protection and flexibility. Chitons are primarily found on rocky substrates in intertidal zones and have a broad, muscular foot that allows them to cling tightly to surfaces. They are herbivorous, feeding mainly on algae using a specialized feeding structure called a radula.

any invertebrate animal with a three-layered body and a pseudocoel

Snail, Octopus, and scallop

No, mollusks are not chordates.

es

An Ammonite is between 240-60 million years ago

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Snails and slugs have lungs, so they can breathe.