Marine Biology: Ocean Features, Fish Anatomy, and Ecosystem Roles

Ocean

A continuous mass of seawater on the earth's surface.

Seas

Smaller and less deep bodies of seawater that are partially enclosed by land.

Taxonomic hierarchy

The classification of species within living organisms by describing the domain, kingdom, phylum, class, order, family, genus, and species.

Binomial nomenclature

The two-part Latin name given to each species, comprising the genus followed by the species.

Dichotomous key

An identification tool utilizing a series of choices between alternative characters, directing to another step in the key until the species is identified.

Biological drawings

A scientific drawing that records and maps important features of the specimen.

Plankton

Microscopic free-floating marine organisms.

Zooplankton

Planktonic consumers that are either floating or weakly swimming animals.

Echinoderms

A marine invertebrate group with pentaradial symmetry and tube feet.

Crustaceans

A marine invertebrate group with a hard exoskeleton, ten jointed legs, and a nauplius larval stage.

Bony Fish

Fish that have a bony skeleton and belong to the class Osteichthyes.

Cartilaginous fish

Fish that have jaws and a skeleton made only of cartilage, belonging to the class Chondrichthyes.

Macroalgae

Marine producers such as kelp and seaweeds.

Marine grasses

Aquatic flowering plants often found in estuarine and coastal environments.

Keystone species

An organism that plays a unique and crucial role in how an ecosystem functions.

Nauplius

Distinctive larval stage of crustaceans.

Pentaradial symmetry

Five arms radiating from a central body cavity.

Tube feet

Tubular projections that assist in locomotion, feeding, and respiration.

Cephalothorax

The part of the exoskeleton that protects the dorsal side.

Gills

The surfaces of gas exchange in fish.

Operculum

A thin flap of skin covering and protecting the gills.

Lateral line

A canal on the head and the side of the fish that contains sense organs.

Scales

Overlapping segments of bone covered by skin found on the outside of fish.

Fins

Protrusions from the body surface that assist in movement, stability, position, reproduction, and protection.

Swim bladder

A buoyancy organ found in bony fish.

Denticles

A type of overlapping scales that provides protection and improved hydrodynamic efficiency in sharks.

Gill slits

External openings from the gills through which water can pass back to the ocean.

Hold fast

Strong, root-like structures that anchor macroalgae to the seabed.

Stipe

A long, tough, vertical stalk of the plants.

Blades

Leaf-like structures that float in the water and absorb light and minerals.

Thallus

A gas-containing structure that provides buoyancy for some species of seaweed.

Roots

Structures of plants that absorb nutrients from sediment.

Rhizomes

A horizontal underground structure that enables seagrasses to reproduce.

Leaf

The photosynthetic organ of plants.

Flower

The sexual reproductive organ of plants.