Skeleton, Skin, and Scales – Vocabulary Flashcards

Vocabulary flashcards covering key terms related to the skeleton, skin, and scales sections of the lecture notes, including osteology, neuro- and branchio-cranial anatomy, vertebral and fin morphology, and integumentary structures.

Osteology

The study of bones.

Neurocranium

The skull portion surrounding the brain and eyes, consisting of the chondrocranium and the dermatocranium.

Chondrocranium

The cartilaginous part of the skull that forms the braincase.

Dermatocranium

Dermal bones that attach to the chondrocranium; derived from scales.

Branchiocranium

The visceral skull (gill arches, jaws, and teeth).

Postcranial skeleton

The skeleton excluding the skull; includes the vertebral column and appendicular skeleton.

Appendicular skeleton

The portion of the skeleton comprising the pectoral and pelvic girdles and their fins.

Notochord

An elastic axial support rod in chordates; primitive in all vertebrates, persists in some adult fishes; largely replaced by intervertebral discs in most adults.

Vertebral column

Series of vertebrae protecting the spinal cord and providing skeletal support.

Monospondylous

Typically one vertebra per body segment.

Diplospondylous

Typically two vertebrae per body segment.

Precaudal

Anterior vertebrae bearing ribs, before the caudal region.

Caudal

Posterior vertebrae beginning with the first vertebra bearing a haemal spine.

Centrum

The main hardened body of a vertebra.

Haemal spine

Spines on the ventral side of caudal vertebrae that support the tail fin.

Neural spine

Dorsal extension of a vertebra that supports the neural arch and fin rays.

Epipleural

A ventrolateral extension of the vertebral arch associated with the rib cage.

Parapophysis

Articulation point on vertebra for ribs.

Pleural rib

Rib that articulates with the vertebral column.

Intercalar

A small bone in the neurocranium (part of otic region in some sketches).

Supraoccipital crest

A crest on the posterior part of the neurocranium's supraoccipital bone that varies among teleosts.

Exoccipital

Occipital elements forming part of the braincase on the back of the skull.

Basioccipital

Basal occipital bone forming part of the braincase floor.

Frontal

Forehead bone of the skull in the neurocranium.

Parietal

Parietal bone—roof of part of the otic region; articulates with frontals and epiotics.

Epiotic

Dermal bone in the otic region of the neurocranium.

Pterotic

Dermal bone of the otic region near the skull roof.

Ethmoid

Ethmoid region of the skull forming part of the anterior braincase.

Parasphenoid

Unpaired dermal bone on the base of the skull; part of the basicranial region.

Basicranial region

Base of the cranium; includes bones like basisphenoid, parasphenoid, and surrounding elements.

Otic region

Part of the neurocranium around the inner ear.

Palatine

Bone of the upper jaw arch (part of the Branchiocranium).

Premaxilla

Anteriormost tooth-bearing bone of the upper jaw.

Maxilla

Upper jaw bone; in some fishes dentigerous, but often excluded from gape in advanced forms.

Supramaxilla

Small bones on the posterodorsal margin of the maxilla.

Dentary

Lower jaw dermal bone bearing teeth.

Angular

Large posterior dermal bone fitting into the dentary's V-shape.

Jaws and teeth

Structures of the Branchiocranium used for grasping and processing food.

Canine

Large conical tooth; often located at the corners of the mouth.

Villiform

Small, fine, closely packed teeth.

Molariform

Pavement-like crushing teeth; forms plates in some rays and fishes.

Incisor

Large cutting teeth with flattened surfaces.

Flattened triangular cutting teeth

Teeth with flattened triangular shapes used for cutting.

Placoid scales

Dermal scales in cartilaginous fishes that resemble teeth and are the basis for their tooth chemistry.

Cosmine

A dentine-like tissue found in cosmoid scales; part of cosmoid skin scales.

Cosmoid scales

A scale type with cosmine in the outer layer and cosmoid tissue; more ancient scale form.

Ganoid scales

Rhombic, hard scales with peg-and-socket joints; found in ray-finned fishes like gars; covered by ganoine.

Ganoine

Inorganic, enamel-like layer coating ganoine scales.

Teleostei scales

Most teleost fish have mostly dermal scales that overlap; include cycloid and ctenoid types; growth by lamellar bone addition.

Cycloid scales

Round to oval scales with smooth margins; lack spines (ctenii).

Ctenoid scales

Scales with posterior spines (ctenii) along the edge.

Placoid scale as teeth derivative

Evolutionary origin: shark teeth are derivatives of placoid scales; homologous to teeth in vertebrates.

Photophores

Light-producing organs used in bioluminescence.

Chromatophores

Pigment cells responsible for color changes in the skin.

Alarm cells

Epidermal cells involved in alarm responses.

Mucous cells

Gland cells in the epidermis that secrete mucus.

Epidermis

Outer skin layer consisting of squamous and cuboidal/columnar cells.

Dermis

Inner skin layer containing blood vessels, nerves, and connective tissue.

Scale shaft

Central stalk of a fish scale.

Stratum compactum

Dense layer within the dermis near the scale region.

Operculum

Gill cover; a large bony plate forming part of the branchiocranium.

Opercular apparatus

The four pairs of dermal bones forming the gill covers.

Gill arches

The four pairs of viscerocranial arches supporting the gills.

Hyoid complex

Five pairs of bones plus branchiostegals that move with the tongue and gill arches.

Branchiostegals

Gill-supported elements that help funnel water through the gill arches.

Adipose fin

Small, fin between the dorsal and caudal fins; typically soft-rayed and without a spine.

Gonopodium

Highly specialized anal fin modified to deliver sperm in some livebearers.

Pectoral girdle

Girdle supporting the paired pectoral fins; not attached to the vertebral column in fishes.

Cleithrum

Largest element of the pectoral girdle.

Posttemporal

Bone linking the skull to the pectoral girdle.

Pelvic girdle

Girdle supporting the paired pelvic fins; usually not attached to the vertebral column in fishes.

Abdominal pelvic position

One of the pelvic fin positions: abdominal (near the abdomen).

Thoracic pelvic position

Pelvic fins lie at the thoracic level.

Jugular pelvic position

Pelvic fins lie near the throat region.

Subabdominal pelvic position

Pelvic fins located below the abdomen.

Dorsal fin

Unpaired fin(s) on the back; stabilizes swimming; may be one or two fins with soft rays and/or spines.

Spines

Rigid, usually unsegmented, protective fin supports.

Soft rays

Flexible, segmented fin rays; form the flexible portion of fins.

Gonopodium (repeat)

Intromittent anal-fin structure in some livebearers.

Adipose fin (repeat)

Small, usually free of strong structural support; function debated.

Anal fin

Unpaired fin on the ventral posterior side; provides stability during swimming; may be modified into a gonopodium in some species.

Photophores (repeat)

Light-producing organs used by many deep-sea fishes.

Pectoral girdle (repeat)

Girdle supporting the pectoral fins; includes the posttemporal and cleithrum.