Ichthyology Lecture 3: General Fish — Skeleton, Skin, and Scales

Vocabulary flashcards covering bone anatomy, otoliths, jaw suspension, branchial arches, scales, and postcranial skeleton in fishes as per lecture notes.

Osteology

The study of bones.

Neurocranium

The braincase; the part of the skull that houses the brain.

Ethmoid bone

Skull bone located between the nasal cavity and orbits.

Orbital region

The area surrounding the eye socket.

Otic region

The skull region associated with the inner ear.

Supraoccipital

A bone at the top rear of the skull’s occipital region.

Exoccipital

Skull bone forming part of the posterior occiput around the foramen magnum.

Basioccipital

Basal portion of the occipital bone.

Parasphenoid

Ventral midline skull bone running under the braincase.

Sphenotic

Skull bone near the orbit forming part of the temporal region.

Prootic

Skull bone located anterior to the otic region.

Pterosphenoid

Wing-like part of the sphenoid region of the skull.

Premaxilla

Front-most bone of the upper jaw.

Maxilla

Upper jaw bone posterior to the premaxilla.

Dentaly

Main bone of the lower jaw.

Dentary

The primary bone of the lower jaw.

Articular

Lower jaw bone that forms the jaw joint with the quadrate.

Quadrate

Jaw element that articulates with the articular; key component of jaw suspension in many fishes.

Palatoquadrate

Upper jaw cartilage in fishes.

Meckel’s cartilage

Lower jaw cartilage in fishes.

Hyomandibula

Bone linking the jaws to the braincase in many fishes.

Autostylic suspension

Jaw suspension where the upper jaw is fused to the braincase with no jet external support from hyomandibula.

Amphistylic suspension

Jaw suspension with two points of articulation between upper jaw and skull.

Hyostylic suspension

Jaw suspension in which the jaw is supported mainly by the hyomandibula.

Holostylic suspension

Primitive jaw suspension where the upper jaw is fused to the braincase (seen in chimaeras).

Operculum

The bony gill cover.

Interopercle

Bone between the operculum and the cheek.

Subopercle

Ventral bone below the operculum.

Mandibular arch

The set of bones forming the lower jaw arch.

Branchial arches

Arches supporting the gills.

Hyoid arch

The arch supporting the tongue and floor of the mouth area.

Ceratohyal

A hyomandibular element of the hyoid arch.

Epihyal

A hyomandibular element on the hyoid arch.

Interhyal

A hyomandibular element connecting to the hyoid elements.

Basihyal

Midline ventral bone of the hyoid apparatus.

Glossohyal

Tongue-supporting element of the hyoid complex.

Urohyal

Ventral element of the hyoid apparatus.

Branchiostegals

Gill-supporting elements along the ventral branchial arches.

Otolith

Ear stones in the inner ear, composed of aragonite and protein, used for balance and hearing.

Sagitta/Sagittae

One otolith (sagitta) in teleosts; used in aging and species identification.

Aragonite

A mineral form of calcium carbonate that makes up otoliths.

Placoid scales

Tooth-like scales with dentine, enamel, and a vascular pulp; typical of sharks.

Ganoid scales

Thick, enamel-bearing scales often rhomboid in gars and relatives.

Cycloid scales

Smooth, round-edged scales with growth rings; common in many teleosts.

Ctenoid scales

Scales with comb-like edges (ctenia).

Dentine

Hard tissue forming the bulk of teeth and some scale bases.

Epidermis

Outer skin layer.

Dermis

Middle skin layer containing scale bases in many fishes.

Hypural

Bones supporting the caudal (tail) fin.

Centrum

The central body of a vertebra.

Neural spine

Dorsal projection (process) on a vertebra.

Haemal spine

Ventral spine on a vertebra (haemal system).

Zygapophysis

Articulating process between adjacent vertebrae.

Parapophysis

Vertebral articulation process for rib attachment.

Ribs

Rib bones articulating with the vertebrae.

Dorsal fin

Fins on the dorsal (back) side.

Anal fin

Fins on the ventral side near the tail.

Caudal fin

The tail fin.

Pectoral fin

Paired fins associated with the shoulder girdle.

Cleithrum

Large bone of the pectoral girdle in fishes.

Postcleithrum

Shoulder girdle bone behind the cleithrum.

Hypocoracoid

Shoulder girdle component near the pectoral girdle.

Branchiocranium

Skull elements derived from the branchial arches.

Otolith rings

Growth rings in otoliths used to estimate age.