animal form and function - annelida, molusca, nematode

Metamere

A repeated body segment in a segmented animal (such as annelids).

Prostomium

The anterior-most part of an annelid’s head, located in front of the mouth, often bearing sensory structures.

peristomium

The body segment surrounding the mouth in annelids.

May have sensory tentacles, jaws, but always has the mouth

setae

bristle like structures used for movement and anchoring to substrate in annelids

septa

internal walls that seperate body segments in segmented worms

parapodia

lateral appaendges used for locomotiona nd respiration in annelids

clitellum

saddle of raised band of secretory cells in segemnted worms (annelids) that secrete gametes

trochophore larva

A free-swimming larval stage found in some annelids and molluscs, characterized by bands of cilia used for movement and feeding

Oligochaete

A class of annelids with fewer setae, including earthworms, usually lacking parapodia.

aortic arches

Muscular blood vessels that pump blood in the circulatory system of earthworms, sometimes called “pseudo-hearts.”

tagmata

Specialised groups of fused body segments that form functional body regions.

Metanephridia

Excretory organs in annelids consisting of tubules that filter coelomic fluid and remove metabolic waste. ANNELIDS and MOLLUSCS

Ventral nerve cord

A long nerve cord running along the underside of the body, connecting segmental ganglia and coordinating movement ANNELIDS

Hemocoel

The main body cavity in molluscs where organs are bathed in hemolymph as part of an open circulatory system.

Mollusc foot

A muscular structure used for locomotion modified differently in each mollusc group. uses waves of muscular contraction

Mollusc head

The anterior region containing sensory organs, mouth, and often the radula

visceral mass

The central body region containing internal organs such as the digestive, reproductive, and excretory systems. consists of mantle, shell and mantle cavity

radula

A rasping feeding structure with rows of microscopic teeth used to scrape or cut food. protudes using protractor muscle

mantle

tissue layer in molluscs that covers the visceral mass- used for gas exchange and secretes clacerous shell

periostracum

outermost layer of mollusc shell

prismatic layer

middle layer of mollusc shell - many endocrinal hormones

nacre

innermost layer of mollusc shell - secreted by mantle, thin sheets of calcium carbonate mixed with organic matter

Odontophore

A cartilaginous support structure beneath the radula that helps move it during feeding

gliding foot

A broad, flat foot used for crawling movement, typical of gastropods (e.g., snails)

hatchet foot

A wedge-shaped foot used for digging or burrowing, typical of bivalves

Mollusc arms

Flexible appendages around the mouth in cephalopods, used for capturing prey and manipulation. - adapted from foot

Ctenidia

“little comb” - The gills of molluscs, used for gas exchange and sometimes feeding. countercurrent system

nerve collar

A ring of nervous tissue surrounding the oesophagus, connecting major nerve cords.

gastropoda

The largest mollusc class including snails and slugs, characterized by torsion during development.

cephalopoda

A class including octopuses, squids, and cuttlefish, with arms/tentacles, large brains, and active predation.

Bivalves

Molluscs with two hinged shells, no radula, and filter-feeding lifestyles (e.g., clams, mussels).

Pseudometamerism

The appearance of segmentation due to repeated structures, but not true segmentation.

Ontogenetic torsion

A 180° twisting of the visceral mass during gastropod development, moving the mantle cavity to the front.

Branchial hearts

Accessory hearts in cephalopods that pump blood through the gills.

Labial palps

Structures near the mouth that sort and transport food particles to the mouth in bivalves

Ecdysis

The shedding (molting) of the cuticle as the organism grows.

Saprozoic

A feeding method where organisms absorb dissolved organic nutrients from their environment.

Coprozoic

Feeding on organic matter in faeces.

Cuticle

A tough, flexible outer covering that protects the nematode and must be shed during growth.

Hypodermis

The layer beneath the cuticle that secretes the cuticle and helps maintain body shape.

Hydrostatic skeleton

A support system where fluid pressure inside the body cavity helps maintain body shape and allows movement.

Amphids

Paired sensory organs located near the anterior end of nematodes used for chemical detection.

Copulatory spicules

Hardened reproductive structures in male nematodes used to hold the female open during mating.

gland cell excretion

A simple excretory system using specialized gland cells to remove metabolic waste in NEMATODES

coleoidea

subclass of cephalopods which include squid, octopus etc

pulmonata

subclass of gastrapoda, includes land and freshwater slugs and snails