Zoology and Marine Biology Vocabulary

Vocabulary definitions covering Porifera, Cnidaria, Arthropoda, Echinodermata, Worms, and Mollusca.

Phylum Porifera

The biological classification for sponges, meaning "pore-bearing."

Osculum

The large, mouth-like opening at the top of a sponge where water exits.

Filter Feeders

Organisms that obtain food by straining small particles out of the water as it passes through their bodies.

Sessile

An organism that is permanently attached to a surface and does not move from place to place as an adult.

Archaeocytes

Amoeba-like cells within the jellylike layer of a sponge that function in digestion, reproduction, excretion, and the secretion of spicules.

Spicules

Hard, needle-like support structures of a sponge made of spongin, silica, or calcium carbonate.

Spongin

A tough, fibrous protein that makes up the flexible skeleton of some sponges.

Gemmules

Seed-like particles containing sponge cells protected by spicules, used for asexual reproduction during harsh conditions.

Fragmentation/Budding

Forms of asexual reproduction where a new sponge grows from a broken piece or a small growth on the parent.

Radial Symmetry

A body plan where parts are arranged around a central axis, like spokes on a wheel.

Nematocysts

Specialized stinging structures used to capture prey or for defense.

Polyp

A tube-shaped, sessile body form of a cnidarian (like an anemone or coral).

Medusa

An umbrella-shaped, free-swimming body form of a cnidarian (like a jellyfish).

Zooxanthellae

Photosynthetic algae that live symbiotically within coral tissues.

Coral Bleaching

A process where stressed corals expel their zooxanthellae, causing them to turn white and potentially die.

Mutualism

A relationship between two species (like clownfish and anemones) where both organisms benefit.

Arthropod

Meaning "jointed foot"; animals characterized by segmented bodies, bilateral symmetry, and exoskeletons with jointed appendages.

Exoskeleton

A rigid external skeleton made of Chitin (and sometimes calcium carbonate) that protects the body and provides support.

Molting (Ecdysis)

The process of shedding the exoskeleton to allow the animal to grow in size.

Segmentation

The division of the body into distinct parts: the Head (sensory), Thorax (movement/legs/wings), and Abdomen (digestion/reproduction).

Mandibles

A pair of mouthparts used specifically for biting, cutting, and chewing food.

Chelicerae

Specialized mouthparts (pincers or fangs) found in the subphylum Chelicerata (spiders, horseshoe crabs).

Carcinisation

A specialized form of evolution where a non-crab crustacean evolves into a crab-like body form.

Metamorphosis

A series of major physical changes from a larval form to an adult form ($\text{Egg} \rightarrow \text{Larva} \rightarrow \text{Pupa} \rightarrow \text{Adult}$).

Castes

Specific groups within social insect societies (like bees or ants) that perform specialized tasks.

Echinoderm

Meaning "hedgehog skin"; marine animals with spiny endoskeletons and radial symmetry as adults.

Endoskeleton

An internal skeleton made of calcium carbonate plates covered by a thin layer of skin.

Water Vascular System

A hydraulic system used by echinoderms for circulation, respiration, and movement.

Tube Feet

Small, fluid-filled muscular tubes used for locomotion, food handling, and breathing.

Pedicellariae

Small, pincer-like structures on the skin used for catching food and removing debris.

Deuterostome

A biological classification based on embryonic development (a trait shared with chordates/humans).

Bioturbators

Organisms (like sea cucumbers) that stir up ocean sediments, helping to recycle nutrients back into the water.

Respiratory Trees

Specialized internal branched tubes in sea cucumbers used for gas exchange and excretion.

Crustaceans

Arthropods with 2 pairs of antennae and compound eyes on stalks (Crabs, Lobsters, Shrimp).

Arachnids

Arthropods with 8 legs and no antennae or wings (Spiders, Scorpions, Ticks).

Hexapods (Insects)

Arthropods with 6 legs and 3 body segments, making up 80% of all arthropods.

Acoelomates

Animals that lack a fluid-filled body cavity between the gut and the body wall (Phylum Platyhelminthes).

Pharynx

A tube-like muscular organ that flatworms extend out of their mouths to release enzymes and suck up food.

Regeneration

The ability to regrow a whole new organism from a small broken piece (asexual reproduction).

Hermaphrodite

An individual that possesses both male and female reproductive organs.

Pseudocoelomates

Animals with a "false" body cavity that is only partially lined with tissue (Phylum Nematoda).

Diffusion

The process by which roundworms move oxygen and nutrients through their bodies in the absence of circulatory/respiratory organs.

Ganglia

Groups of nerve cell bodies that act as a simple "brain" for responding to stimuli.

Trichinosis

A disease caused by Trichinella worms, usually contracted by eating undercooked pork.

Coelomates

Animals with a true, fully lined body cavity (Phylum Annelida).

Setae

Tiny bristles that help segmented worms (like earthworms) move and anchor themselves.

Parapodia

Paddle-like structures used by marine worms (Polychaetes) for swimming and crawling.

Closed Circulatory System

A system where blood is confined to vessels (Annelids have "hearts" to pump blood).

Anticoagulant

A substance in a leech's saliva that prevents blood from clotting while it feeds.

Mantle

A membrane that surrounds the internal organs and, in many mollusks, secretes calcium carbonate to form a shell.

Radula

A tongue-like organ with rows of teeth used to scrape food into the mouth.

Open Circulatory System

A system common in Gastropods and Bivalves where blood is pumped into open spaces surrounding the organs.

Torsion

The developmental process in snails that results in a coiled shell.

Detritivores

Organisms (like land slugs) that feed on dead organic matter.

Bivalve

An organism with "two shells" joined by a hinge (Clams, Oysters, Mussels).

Siphons

Tubular structures used to draw water in and out for filter feeding and respiration.

Bioaccumulation

The buildup of toxins (like those from red tides) in a bivalve’s flesh, which can cause Shellfish Poisoning in humans.

Chromatophores

Pigment-containing cells that allow cephalopods to change color for camouflage or communication.

Jet Propulsion

Movement created by forcing water out of a siphon (Class Cephalopoda).

Teuthology

The specific study of cephalopods.

Convergent Evolution

The process where unrelated species (like cuttlefish and humans) independently evolve similar traits (like complex eyes).