Ichthyology Exam 1 Vocabulary Definitions

Vocabulary practice flashcards generated from the Ichthyology Exam 1 study guide covering systematics, anatomy, physiology, and chondrichthyan evolutionary biology.

Parsimony

Preference for the simplest evolutionary explanation requiring the fewest changes.

Science

A systematic method of acquiring knowledge through observation, hypothesis testing, and evidence.

Type I error

Incorrectly concluding a difference exists (false positive).

Type II error

Failing to detect a real difference (false negative).

Evolutionary systematics

Classification using ancestry and overall similarity.

Hagfish/Lampreys

Living jawless vertebrates (agnathans).

Chondrichthyans

Cartilaginous fishes including sharks, rays, and chimaeras.

Osteichthyans

Bony fishes and their descendants.

Actinopterygians

Ray-finned fishes.

Sarcopterygians

Lobe-finned fishes including tetrapod ancestors.

Sauropsid amniotes

Reptiles and birds.

Synapsid amniotes

Mammals and their extinct relatives.

Cladistics

Classification based on shared derived characters.

Synapomorphy

Shared derived character defining a clade.

Symplesiomorphy

Shared ancestral character.

Homoplasy

Similarity not due to common ancestry.

Clade

Ancestor and all descendants.

Sister group

Closest relative lineage of another lineage.

Cladogram

Diagram of hypothesized evolutionary relationships.

Monophyly

Containing an ancestor and all descendants.

W. Hennig

Willi Hennig, founder of cladistics.

Dinosauria

Clade containing dinosaurs, including birds.

Archosauria

Crocodilians, birds, dinosaurs and relatives.

Phanerozoic

Current eon of visible life.

Paleozoic

Era from 541-252 million years ago.

Mesozoic

Era from 252-66 million years ago.

Cenozoic

Era from 66 million years ago to present.

Ecto/Endo/Mesoderm

Three embryonic germ layers.

Protostomes

Animals whose blastopore becomes the mouth.

Deuterostomes

Animals whose blastopore becomes the anus.

Endostyle

Mucus-secreting chordate structure homologous to thyroid.

Collagen/Elastin/Keratin

Structural proteins of connective tissue, elastic tissue, and skin/hair/scales.

Hydroxyapatite

Mineral component of bone and teeth.

Haversian canals

Central canals in compact bone containing blood vessels and nerves.

Endochondral bone

Bone formed by replacing cartilage.

Notochord

Flexible axial support rod of chordates.

Tooth whorl

Series of replacement teeth arranged in a spiral row.

Myomere

Segmented block of muscle.

Cloaca

Common chamber for digestive, urinary, and reproductive tracts.

W-shaped myomeres

Complex muscle blocks typical of vertebrates.

V-shaped myomeres

Simpler muscle blocks in amphioxus.

Portal veins

Veins connecting two capillary beds.

Opisthonephros

Adult kidney of most fishes and amphibians.

Archinephric duct

Primitive kidney duct draining urine.

Metanephros

Adult kidney of amniotes.

Oviparous/Viviparous

Egg-laying/live-bearing reproduction.

Peripheral nervous system

Nerves outside brain and spinal cord.

CNS

Central nervous system; brain and spinal cord.

Anadromous

Migrates from sea to freshwater to reproduce.

Conodonts

Extinct eel-like vertebrates known from tooth-like fossils.

Ostracoderms

Extinct armored jawless fishes.

SNS

Somatic nervous system controlling voluntary movement.

Placoderms

Extinct armored jawed fishes.

Acanthodians

Extinct spiny fishes.

Ammocoetes larvae

Larval stage of lampreys.

Buccal pumping

Ventilation using mouth and operculum movements.

Pleurodont teeth

Teeth attached to inner side of jaw.

Acrodont teeth

Teeth attached to jaw crest.

Thecodont teeth

Teeth set in sockets.

Lateral line system

Mechanosensory system detecting water movement.

Ram ventilation

Swimming with mouth open to force water across gills.

Ultrafiltrate

Initial kidney filtrate lacking cells and large proteins.

Counter-current exchange

Opposing flow system maximizing transfer efficiency.

Ampullae of Lorenzini

Electroreceptors of sharks and rays.

Rete mirabile

Countercurrent vascular network.

Endothermy

Internal metabolic heat production.

Neuromast organ

Sensory unit of the lateral line.

Ectothermy

Dependence on environmental heat.

Iso/Hypo/Hyper-osmolal

Same/lower/higher solute concentration than reference fluid.

Ammonotelism

Excretion primarily as ammonia.

Ureotelism

Excretion primarily as urea.

Regional heterothermy

Maintaining elevated temperatures in specific body regions.

Chondrichthyes

Class containing sharks, rays, and chimaeras.

Holocephali

Chimaeras or ratfishes.

Elasmobranch

Sharks and rays.

Ingroup/Outgroup

Taxa being analyzed and reference taxa outside the group.

Parallel evolution

Independent evolution of similar traits in related lineages.

Cladoselache

Early stem chondrichthyan shark-like fish.

Hyostylic jaw

Jaw suspension supported primarily by hyomandibula.

Hybodus

Mesozoic shark-like chondrichthyan genus.

Heterodont dentition

Different tooth types in same mouth.

Squaloids/Galeoids

Major modern shark groups.

Sensory feeding adaptations

Specialized sensory systems aiding prey detection.

Autostylic jaw

Jaw suspension fused directly to skull.

Lecithotrophy

Embryo nourished by yolk.

Ovoviviparity

Eggs hatch within mother; nutrition mainly from yolk.

Matrotrophy

Embryo receives nutrients directly from mother.

Viviparity

Live birth with maternal support.

Skates and rays

Flattened elasmobranch fishes.