What is the larval stage of a mollusk

Both mollusks and annelids develop through a larval stage called a trochophore larva. Trochophore larvae are characterized by having a band of cilia that wraps around the body.

What are the 3 main mollusk larval stages?

In some mollusks, the zygote hatches and undergoes two larval stages, trochophore and veliger, before becoming a young adult; bivalves may exhibit a third larval stage, glochidia.

How are mollusks born?

HOW DO MOLLUSKS REPRODUCE? Mollusks reproduce sexually. Slugs and snails are hermaphrodites (possessing both male and female organs), but they must still mate to fertilize their eggs. Most aquatic mollusks lay eggs that hatch into small, free-swimming larvae called veliger.

What kind of larvae do molluscs have?

A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells.

What is the larval stage of echinoderms?

Echinoderms show a complicated metamorphosis in the course of development. Their larva is strikingly bilaterally symmetrical whereas the adult shows radial symmetry. Larva swims with the help of ciliated bands , which may be complicated by a number of short or long slender projections or arms from the body wall.

Do molluscs have trochophore larvae?

trochophore, also called trochosphere, small, translucent, free-swimming larva characteristic of marine annelids and most groups of mollusks. … In some mollusks (such as gastropods and bivalves), the trochophore develops into a second stage, the veliger (q.v.), before metamorphosing to adult form.

What is the larva of Arthropoda?

This larval stage, called a nauplius, is found in barnacles, copepods, penaeid shrimps, and ostracods. It swims by using its jointed appendages that are moved by muscle contraction. These larvae have a nauplier eye, made up of photoreceptor cells that are thought to give rise to the photoreceptors in some adult forms.

What is Glochidium larva?

The glochidium (plural glochidia) is a microscopic larval stage of some freshwater mussels, aquatic bivalve mollusks in the families Unionidae and Margaritiferidae, the river mussels and European freshwater pearl mussels.

What is the larval form of Hemichordata?

A tornaria is the planktonic larva of some species of Hemichordata such as the acorn worms.

Which larval stage is shelled and shows the beginning of a foot and mantle?

The larvae (which develop from ciliated, free-swimming trochophore larvae) have the beginnings of a foot, shell and mantle. In many molluscs the trochophore larval stage is passed in the egg, and the veliger hatches to become the only free-swimming stage.

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What is the life cycle of Mollusca?

In some mollusks, the zygote hatches and undergoes two larval stages—trochophore and veliger—before becoming a young adult; bivalves may exhibit a third larval stage, glochidia.

What is the method of mollusks?

Mollusks reproduce sexually, and most species have separate sexes. Sexual reproduction is achieved by the formation and fusion of gametes: sperm and eggs. Some species are hermaphrodites meaning that individuals are capable of forming both sperm and eggs.

Is a larval form phylum echinodermata?

➢ Echinoderms are deuterostomes and hence cleavage is radial, holoblastic and indeterminate. ➢ The larvae hatch in water and feed and grow through successive larval stages to become adults. ➢ The larvae of echinoderms are bilaterally symmetrical but lose symmetry during metamorphosis.

What are the larval forms of asteroidea?

The earliest larval stage of Asteroidea is called an auricularia, followed by bipinnaria and brachiolaria stages. Larval development is illustrated with Asterias rubens, a common sea star in the North Sea.

What is bipinnaria larva in zoology?

From Wikipedia, the free encyclopedia. A bipinnaria is the first stage in the larval development of most starfish, and is usually followed by a brachiolaria stage. Movement and feeding is accomplished by the bands of cilia.

What is the larval stage called?

The larva, often referred to as a nymph, has more or less the same organization as the adult, or imago; it feeds in a similar way but differs from the adults in lacking wings and in having incomplete sex organs.

What is the larval stage of crab?

Most crabs develop through a few stages (usually 2 to as many as 8 or 9, depending on the group) of planktonic zoea larvae. The final zoea larva then moults into a still-swimming larva called a megalopa, which is morphologically and ecologically a transitional phase between the planktonic zoeae and the benthic adult14.

What is the larval stage of a crustacean called?

In crustaceans the larva, called nauplius, does not differ substantially in mode of life or means of locomotion from the adult but has fewer appendages than the adult. A typical crustacean nauplius has three pairs of legs and an unpaired simple eye.

What phylum are trochophore larvae?

They are triploblastic, bilaterally symmetrical and segmented Metazoa. Some of the annelids belong to the Lophotrochozoa lineage. Trochophore larva occurs in phylum annelida.

What phylum has a trochophore larva?

Trochophores exist as a larval form within the trochozoan clade, which include the entoprocts, molluscs, annelids, echiurans, sipunculans and nemerteans. Together, these phyla make up part of the Lophotrochozoa; it is possible that trochophore larvae were present in the life cycle of the group’s common ancestor.

Does cephalopod have trochophore stage?

All conchiferans except cephalopods also possess a similar topological arrangement of cerebral, pedal, pleural and buccal ganglia (the latter have been lost in Bivalvia) and a trochophore-like larva is present in all molluscs except for the cephalopods that exhibit direct development (the life cycle of monoplacophorans …

What is the larval stage of Cephalochordata?

1. Larval tunicates swim for a few days after hatching, then attach to a marine surface and undergo metamorphosis into the sessile adult form. Lancelets (Cephalochordata) are marine organisms that possess all features of chordates; they are named Cephalochordata because the notochord extends into the head.

What is phylogeny of Hemichordates?

The phylogenetic relationships within Hemichordata are significant for understanding the evolution of the deuterostomes. … At present, Hemichordata is divided into two classes, the solitary, free-living enteropneust worms, and the colonial, tube- dwelling Pterobranchia.

What is the larva of Balanoglossus?

Balanoglossus is a hemichordate and yes, its larva is called tornaria.

What is Megalopa larva?

Megalopa larva It has a broad and crab-like unsegmented cephalothorax. The carapace is produced anteriorly into a median spine. The eyes are large, stalked and compound. All the thoracic appendages are well formed of which the last 5 pairs are uniramous.

What is Cydippid larva?

cydippid larva A free-swimming, larval stage of a ctenophorid (Ctenophora) which resembles adults of the order Cydippidea. A Dictionary of Zoology.

What is Parenchymula larva?

Parenchymula is the larval stage found in phylum Porifera. Among all the options, Leucosolenia belongs to phylum Porifera while Hydra belongs to phylum Coelentrata, Ascaris belongs to phylum Nematoda and Pheretima belongs to phylum Annelida. So, the correct answer is ‘Leucosolenia’.

Do mollusks go through larval stages?

Both mollusks and annelids develop through a larval stage called a trochophore larva. Trochophore larvae are characterized by having a band of cilia that wraps around the body.

What is mantle in phylum Mollusca?

The mantle (also known by the Latin word pallium meaning mantle, robe or cloak, adjective pallial) is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.

What is the difference between mollusc and mollusk?

As nouns the difference between mollusk and mollusc is that mollusk is (us) (mollusc) while mollusc is a soft-bodied invertebrate of the phylum mollusca, typically with a hard shell of one or more pieces.

How are gametes released in molluscs?

Mollusks are primarily of separate sexes, and the reproductive organs (gonads) are simple. … Most reproduction, however, is by sexual means. Eggs and sperm are released into the water by members of some (primitive) species, and fertilization occurs there.