Phylum Mollusca

Phylum Mollusca Classes (from lecture)

Class Caudofoveata Class Solenogaster Class Monoplacophora Class Polyplacophora Class Scaphopoda Class Gastropoda Class Bivalvia Class Cephalopoda

Reproduction?

- Sexual; dioecious - Pair of gonads empties gametes into excurrent siphon. - Some are Monecious, both sexes. Like in snails.

Germ Layers and Development?

- Three germ layers: ecto-, meso-, endoderm - Protostome

Largest classes of molluscs are?

Gastropoda (snails and their relatives), Bivalvia (clams, oysters, and others), Polyplacophora (chitons), and Cephalopoda (squids, octopuses, nautiluses).

Which have undergone torsion? Detorsion?

Gastropods Opisthobranchia (sea hares & sea slugs) and the land slugs of the Pulmonata

How many of these specimens posses a radula (horny tooth-bearing strip on the tongue of molluscs that is used for rasping food)?

Gastropods, Cephalopoda, Mono-, A- & Polyplacophora

Class Monoplacophora

Kingdom: Animalia Phylum: Mollusca (unranked): Monoplacophora Odhner, 1940 Big Characteristics: Serially repetition

Nervous system?

Limited cephalization, except cephalopods, which have giant nerve cells, complex sensory system with image forming eyes and complex behavior.

Name the main function of the mantle?

Mantle secretes the shell.

Excretory system? How does it poop?

Nitrogenous wastes excreted into excurrent siphon by pair of kidneys; some ammonia eliminated by ctenidia.

Which specimens have lungs? (Just have think of which live on land vs. in water......)

Pulmonata - their name gives this away.

Name a class used for currency?

Scaphopoda.

The molluscs include a number of familiar animals, including?

Snails, oysters, clams, octopuses and squids.

Trocophore?

The planktonic larva .

Coelom and Body Organization?

Well-developed coelom

Defense?

- Burrowing with muscular foot; hard exoskeleton (shell-reduced in cephalopods). - Ink used by some cephalopods.

Digestive system?

- Complete; specialized for filtering small food particles from water. - Cilia lining ctenidia draw water into mantle cavity through incurrent siphon; from mantle, labial palps direct food to mouth; esophagus, stomach, digestive glands; waste exits anus into excurrent siphon.

Molluscs are probably closest phylogenetically to?

Annelids (earthworms or leech).

Name the oldest part of a univalve shell? Bivalve?

Apex for Univalve, Umbo for bivalve but often the terms are used interchangeably.

Symmetry?

Bilateral

Which evolved from sea and moved on to brackish and freshwater habitats?

Bivalves and gastropods.

Which ones are filter feeders?

Bivalvia (Scaphopoda....have a captacula)

Veliger?

Final larval stage.

Skeletal system?

Hard exoskeleton; outer organic layer rests on layers of calcium carbonate; exoskeleton reduced or absent in most cephalopods.

Class Bivalvia means?

Hatchet foot

Class Cephalopoda means?

Head foot.

All molluscs are characterized by having three main body regions?

Head-foot, which is the sensory and locomotor part of the body; a visceral mass, containing most of the organ systems; and a mantle, which covers the visceral mass and secretes the shell.

Cephalopoda is characterized by?

Its bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot.

Class Polyplacophora means?

Many plates on a foot.

Smaller classes molluscs are?

Monoplacophora, Scaphopoda (tusk shells), Caudo- foveata, and Solenogastres.

Locomotion?

Muscular foot

Circulatory system?

Open circulatory system; hemocyanin dissolved in plasma; lymphocytes present; a few bivalves and gastropods use hemoglobin and have erythrocytes; dorsal heart beats rhythmically to create pressure; hemolymph forced into aorta and carried into tissues by open vessels.

Most molluscs also have?

Radula, a rasping structure covered with chitinous teeth, which is used in feeding.

Respiratory system?

Sinuses collect hemolymph and transport to ctenidia for gas exchange..

Class Gastropoda means?

Stomach

Ancestral Larvae Is a Trocophore; Some Produce a Veliger

Synapomorphies

Gastropods, Bivalves, Cephalopods, And Chitons

Synapomorphies

More Species Of Molluscs In Ocean Than Any Other Phylum, Over 200,000 Sp.

Synapomorphies

Most Have A Head With Eyes

Synapomorphies

Open Circulatory System

Synapomorphies

Soft Bodied; Many With Protective Shell

Synapomorphies

The Foot Allows Locomotion Or Attachment

Synapomorphies

The Mantle Is A Thin Tissue Layer Covering Body That Secretes Shell

Synapomorphies

The Radula Is A Tooth Like Structure Used For Feeding

Synapomorphies

Annelids and molluscs have very similar developmental patterns and a similar type of ciliated larva, called a?

Trochophore larva. But not segmented like annelids.

Larval Forms?

Trocophore and Veliger

Class Scaphopoda means?

Tusk shell

What does sapient mean?

Wise, capable of emotional knowledge.