Mollusca Characteristics and Classification

A characteristic of members of the phylum Mollusca, it is a soft body often covered by a shell. Molluscs are known for their diverse forms, including snails, slugs, mussels, and octopuses.

A specialized epidermal tissue that secretes the shell in molluscs. It's essential for their protection and structure.

A class of molluscs that includes snails and slugs.

A broad, tongue-like organ with rows of teeth found in the mouth of gastropods. It helps them scrape food.

A muscular structure that allows gastropods to move. It's located on the underside of the body.

Air-filled sacs in terrestrial snails that allow them to breathe. They are analogous to lungs in other animals.

Feathery structures in aquatic snails used for extracting oxygen from water.

An opening on the body surface of a snail that allows air or water to enter and exit the respiratory system.

The fluid that circulates in the open circulatory system of snails, carrying nutrients and oxygen.

A pair of excretory organs in snails that filter waste products. They are similar to kidneys in other animals.

A series of interconnected nerve cell clusters in the snail's body that act as the central nervous system.

Sensory organs on the snail's head used for detecting chemical changes in the environment.

Organs of balance in snails that help them sense gravity and orientation.

A group of mollusks characterized by two hinged shells (valves) connected by a ligament.

Bivalves lack a distinct head, tentacles, and radula (a tongue-like structure with teeth).

Many Bivalves have reduced heads and lack traditional feeding structures like tentacles and a radula. They filter food particles from the water using their gills.

Bivalves have an open circulatory system, where hemolymph (blood-like fluid) flows throughout the body and bathes the organs.

Bivalves have two siphons: an incurrent siphon that brings water into the body cavity, and an excurrent siphon that expels water after oxygen is taken in by the gills.

Bivalves have a pair of nephridia (kidneys) which filter waste products from the hemolymph and excrete urine through a nephridiopore.

Bivalves have a simple nervous system consisting of ganglia (nerve cell clusters) connected by nerve fibers. They lack a centralized brain.

The lunule is a crescent-shaped depression on the dorsal surface of the shell, used for identification of different species.

A structure in cephalopods that helps them grind and crush food.

The organ in cephalopods that pumps blood to the gills.

The organ in cephalopods that pumps oxygenated blood to the rest of the body.

A protein containing copper used by cephalopods to transport oxygen in their blood.

The organs in cephalopods responsible for filtering nitrogenous waste from the blood.

The most intelligent group of invertebrates, known for their complex nervous systems and large brains.

Octopuses have complex eyes that allow them to see in low light and possibly distinguish colors. They are similar to human eyes but with a W-shaped pupil.

Nautilus, a cephalopod, uses its statocysts to detect sound and helps it maintain balance.

Cephalopods like cuttlefish can change color patterns within milliseconds for communication, camouflage, or warning signals. Specialized cells called chromatophores expand and contract to create the visuals.

A defense mechanism used by cephalopods (except Nautilus). A cloud of dark inky fluid is ejected to confuse predators

Sepia latimanus (broadclub cuttlefish) can shift its color from camouflage tan to yellow with dark highlights in less than a second.

Cephalopods have a diverse reproductive system, with most having external fertilization. Only octopuses have internal fertilization.

The male octopus has a specialized arm called a hectocotylus used to deliver sperm into the female's siphon during fertilization.

Before mating, the male octopus wraps his arm around the female, securing her in a "neck" or "mouth-to-mouth" position, depending on the species.

The process by which a female octopus stores sperm from a male until her eggs are mature and then fertilizes them.

Female octopuses release their eggs in clusters, each egg enclosed in a protective coating.

The act of a female octopus eating the male after mating.

A form of locomotion used by many cephalopods, where they expel water from a siphon to propel themselves forward.

Different-looking males and females within a species. In octopuses, females are usually larger than males.

The natural habitat of cephalopods, as they are found in all oceans and seas around the world.

A group of marine animals that includes octopuses, squid, cuttlefish, and nautilus, known for their intelligence and complex behaviors.

A type of propeller-driven waterjet system used for propulsion. This system is more efficient than a rocket engine.