bio of fish exam 1 condensed

Ichthyology

The scientific study of fishes.

Fisheries science

The study and management of fish populations using biology, ecology, economics, and policy.

Current course definition of a fish

A mostly gill-breathing, usually finned craniate poikilotherm that is more primitive than an amphibian.

Why is “fish” difficult to define?

Fishes are extremely diverse and do not form one true monophyletic group; the term is convenient rather than a formal taxon.

Fish vs. fishes

Fish means one or more individuals of one species; fishes means individuals belonging to multiple species.

Craniate

An animal with a cranium or skull.

Poikilotherm

An animal whose body temperature changes substantially with the environmental temperature.

Aristotle

First known ichthyologist; described 117 fishes, separated fishes from cetaceans, and studied fish anatomy.

Peter Artedi

Father of Ichthyology; standardized fish classification, measurements, and counts.

Carolus Linnaeus

Adapted Artedi’s classification into Systema Naturae and established the basis of modern binomial nomenclature.

Georges Cuvier

Important comparative anatomist who classified the fishes known during his time.

Louis Agassiz

Classified fossil fishes and made major contributions to paleontology and ichthyology.

David Starr Jordan

Major American ichthyologist who described many fish taxa and trained later ichthyologists; he also promoted eugenics.

Carl L. Hubbs

Influential American ichthyologist known for fish classification and Great Lakes fish research.

Rosa Smith Eigenmann

Early American female ichthyologist who described 35 genera and more than 150 species.

Eugenie Clark

Pioneered shark behavior and SCUBA-based fish research and promoted marine conservation.

Taxonomy

The description, identification, naming, and classification of organisms.

Systematics

The study of biological diversity and evolutionary relationships among organisms.

Alpha taxonomy

The discovery, description, and naming of species.

Beta taxonomy

The arrangement of species into a natural classification system.

Gamma taxonomy

The study of variation within a species and the evolutionary processes producing it.

Morphospecies concept

Species are separated using a unique combination of physical or morphological characters.

Biological species concept

A species consists of populations that can interbreed and are reproductively isolated from other groups.

Evolutionary species concept

A species is an ancestor-descendant lineage that maintains its own identity and evolutionary fate.

C. Tate Regan

Scientist associated in the lecture with the morphospecies concept.

Ernst Mayr

Scientist associated with the biological species concept and the alpha, beta, and gamma stages of taxonomy.

E. O. Wiley

Scientist associated with the evolutionary species concept.

Willi Hennig

Introduced cladistics, also called phylogenetic systematics.

Cladistics

Classification based on shared derived characters and common ancestry.

Clade

A common ancestor and all of its descendants.

Monophyletic group

A group containing a common ancestor and every one of its descendants.

Paraphyletic group

A group containing a common ancestor but leaving out one or more descendants.

Polyphyletic group

A group made from separate lineages without including their most recent common ancestor.

Plesiomorphy

An ancestral character state.

Apomorphy

A derived or evolutionarily newer character state.

Synapomorphy

A shared derived character that supports a clade.

Autapomorphy

A derived character unique to one taxon.

Homology

Similarity inherited from a common ancestor.

Homoplasy

Similarity that evolved independently, usually through convergence, rather than being inherited from a common ancestor.

Outgroup

A related taxon outside the group being studied, used to determine which character states are ancestral.

Holotype

The single original specimen designated as the name-bearing example of a new species.

Paratype

An additional specimen included in the original species description to show variation; it is not the name-bearing specimen.

Syntypes

Multiple original name-bearing specimens used when the author did not designate one holotype.

Lectotype

One syntype later selected to become the single name-bearing specimen.

Paralectotype

Any remaining syntype after one syntype has been chosen as the lectotype.

Neotype

A new name-bearing specimen selected when the original type material is lost or destroyed.

Topotype

A specimen collected from the same location as the original type specimen; it is not automatically a name-bearing type.

Type locality

The geographic location where the name-bearing type specimen was collected.

Principle of Priority

The oldest properly published available scientific name normally has priority.

Junior synonym

A newer scientific name for a taxon that already has an older valid name.

Scientific authority in parentheses

The species has been moved to a different genus from the one in which it was originally described.

Four major reasons scientific names change

Species are split, species are lumped, classification changes, or an older valid name is discovered.

Meristic character

A countable trait that usually remains stable with size, such as fin rays, vertebrae, scales, or gill rakers.

Morphometric character

A measured body dimension, such as head length, body depth, or eye diameter.

Roman numerals in fin formulas

Represent fin spines.

Arabic numerals in fin formulas

Represent soft fin rays.

Order ending

-iformes.

Suborder ending

-oidei.

Family ending

-idae.

Subfamily ending

-inae.

Tribe ending

-ini.

Epidermis

The outer, ectoderm-derived layer of fish skin.

Dermis

The deeper, mesoderm-derived skin layer containing blood vessels, pigment cells, glands, and sensory structures.

Main functions of fish mucus

Reduces friction and forms a physical and chemical barrier against injury, pathogens, and parasites.

Chromatophore

A pigment-containing or light-reflecting cell responsible for fish coloration.

Countershading

Dark coloration on top and light coloration underneath, making a fish harder to see from above and below.

Placoid scale

A tooth-like dermal denticle of sharks and rays that is replaced rather than enlarged as the fish grows.

Ganoid scale

A hard, usually diamond-shaped scale with a ganoine surface and peg-and-socket connections; found in gars and some basal bony fishes.

Cosmoid scale

A thick ancestral lobe-finned-fish scale composed of several layers, including bone, cosmine, and a hard outer covering.

Cycloid scale

A thin, flexible overlapping scale with a smooth rear edge.

Ctenoid scale

A thin, flexible overlapping scale with small comb-like spines called ctenii on its rear edge.

Leptoid scale

The thin flexible overlapping scale of teleosts; cycloid and ctenoid scales are the two major forms.

Deciduous scales

Scales that are easily shed, as in herrings and anchovies.

Circuli

Growth ridges on a fish scale.

Annulus

A scale growth mark representing a period of slow growth and commonly interpreted as approximately one year.

Three types of skeletal calcification in living fishes

Globular, prismatic, and areolar calcification.

Globular calcification

Small spherical deposits of hydroxyapatite; occurs in all major fish groups.

Prismatic calcification

Dense perichondral mineralization arranged in prisms; characteristic of elasmobranchs and holocephalans.

Areolar calcification

Concentric mineralized layers in elasmobranch vertebral centra that can be used for age estimation.

Axial skeleton

The cranium and vertebral column; it protects nervous tissue and anchors muscles.

Appendicular skeleton

The pectoral and pelvic girdles and their fin-support structures.

Neurocranium

The braincase that protects the brain and major sensory organs.

Branchiocranium

The visceral skeleton supporting the jaws, gills, tongue, and pharyngeal region.

Mandibular arch

The visceral arch that forms the upper and lower oral jaws.

Hyoid arch

The suspensory arch connecting the lower jaw and opercular apparatus to the skull and helping support respiration.

Opercular apparatus

Four pairs of flat dermal bones forming the bony gill-cover system: opercle, preopercle, subopercle, and interopercle.

Main functions of the opercular apparatus

Protects the gills and helps pump water across them.

Branchial arch

A gill-support arch bearing gill rakers, gill filaments, pharyngeal tooth patches, and supporting bones.

Pharyngeal jaws

Modified branchial-arch structures used to crush, grind, hold, or transport food.

Neural arch and neural canal

The dorsal part of a vertebra that surrounds and protects the spinal cord.

Neural spine

The elongated projection extending upward from a vertebra.

Parapophysis

A projection from a vertebra that provides an attachment or articulation point for a rib.

Haemal canal and haemal spine

The ventral vertebral canal protects major blood vessels; in posterior vertebrae, its arch extends into a haemal spine.

Precaudal vertebra

An anterior trunk vertebra that normally bears ribs.

Caudal vertebra

A posterior tail vertebra bearing an elongated haemal spine.

Monospondylous vertebrae

One vertebral centrum occurs per body muscle segment; generally found in the anterior region of elasmobranchs.

Diplospondylous vertebrae

Two vertebral centra occur per body muscle segment; generally found from the pelvic region into the tail of elasmobranchs.

Protocercal tail

The vertebral axis extends straight to the tail tip, producing a symmetrical primitive tail.

Heterocercal tail

The vertebral column enters the larger upper tail lobe, making the upper and lower lobes structurally unequal.

Homocercal tail

The external tail lobes appear approximately equal, although internal skeletal support is asymmetrical.