Mighty. Scraping teeth Body of Mollusc Molluscs The life cycle of many marine mollusks includes a ciliated larvae, the ____trochophore___________.

mighty

Scraping teeth

Body of Mollusc

Molluscs• The life cycle of many marine mollusks includes a

ciliated larvae, the ____trochophore___________.– This larva is also found in marine __annelids_____

(segmented worms)

A trochophore larva.

• Marine; oval shapes and shells divided into eight dorsal plates.

• Muscular __foot_ grips the rocky substrate tightly and creep.

• Grazers; use _radula__ to scrape and ingest algae.

Class of Polyplacophora - chitons

Class ______Gastropoda____ • More than 75,000 species; mostly marine, but

also many freshwater species.• _Some Terrestrial___

– Garden snails and slugs have adapted to land.

In place of the gills found in most aquatic gastropods, the lining of the mantle cavity of terrestrial snails functions as a lung

Class of Gastropoda

• Most gastropods are protected by _______shells_____ into which the animals can retreat if threatened.– Other species have lost their shells entirely and may

have _chemica_ defenses against predators (They can handle the nematocysts from anemones).

Shell-less nudibranchs

Class of Gastropoda

• Many gastropods have distinct heads with ___barbs__ at the tips of tentacles.

Queen Conch

Class ____Bivalvia__

• ____Two_ shells connected with a hinge.

• Clams, oysters, mussels, and scallops.

• Bivalves have shells divided into two halves.– The two parts are hinged at the mid-dorsal line, and

powerful adductor muscles close the shell tightly to protect the animal.

– When the shell is open, the bivalve may extend its hatchet-shaped foot for digging or anchoring.

Class Bivalvia

• The mantle cavity of a bivalve contains gills that are used for feeding and gas exchange.

• Most bivalves are filter feeders, trapping fine particles in mucus that coats the gills.– The Palp conveys the

particles to the mouth.– Water flows into mantle

cavity via the incurrent

siphon, and passes over the gills, and exits via the

Excurrent siphon.

Class of __Cephalopoda____ • __head_-Footed Molluscs

Use quick movements to dart toward their prey which they capture with several long tentacles. – Squids and octopuses use beaklike mouths to bite

their prey and then inject poison to immobilize the victim.

• A mantle covers the organs; shell is reduced and internal in squids, missing in many octopus. Onlychambered-nautilus

has external shell.

• Fast movements by a squid occur when it contracts its mantle cavity and fires a stream of water through the excurrent siphon.– By angling the siphon in different directions, the

squid can rapidly move in different directions.

• The foot of a cephalopod (“head foot”) has been modified into the muscular siphon and parts of the tentacles and head.

This is the chambered nautilus, a type of Cephalopod, with up to 90 short tentacles used to capture prey

A series of gas-filled chambers serve as a bouyancy device

• Unique among mollusks, cephalopods have a closed circulatory system to facilitate the movements of gases, fuels, and wastes through the body.

• They have a well-developed nervous system with a complex brain and well-developed sensory organs.– This supports learning and problem solving

behavior.

Highly developed eyes in cephalopods