Unit 1

Notochord

rod-like structure that supports and protects the spinal cord in chordate animals

'Ostracoderms'

jawless fishes, not monophyletic, body covered in dermal bone, cartilaginous skeletons

Anadromous

fish migrating up raivers from the sea to spawn

Otolith

stones in ear, registers gravity and linear acceleration

Horizontal septum

transverse wall of tissue that can occur anywhere in the body

Ampullae of Lorenzini

special sensing organs called electroreceptors, forming a network of jelly-filled canals; these organs help sharks sense electric fields in the water

Heterocercal tail

In some fishes, a tail with the upper lobe larger than the lower, and the end of the vertebral column somewhat upturned in the upper lobe, as in sharks.

Natural History

the study of animals, plants and their environment, focused more on observation than experiments

Taxonomy

the science of classification of living and extinct organisms

Homoplasy

shared characteristic that evolved independently in different groups of animals

Myomeres

muscle segments found in aquatic chordates

Chondrocranium

the cartilaginous skeletal structure of the fetal skull that grows to envelop the rapidly growing embryonic brain

Dermatocranium

portion of the cranium that is composed of dermal bone, part of the skull that develops int he form of membrane bone

‘Dunkleosteus’

jointed neck fish, covered in dermal bone

'Acanthodians'

spiny sharks, spines on most fins

Ammocoetes

filter-feeding larval form of a lamprey

Batoidea

flat-bodies, cartilaginous fish, suborder of cartilaginous fishes known as rays

Cephalic claspers

found on the head or near the cephalic region, assist in making by providing grip or positioning during copulation

Pelvic claspers

male anatomical structure used in mating, formed from the posterior portion of their pelvic fin, serves as a channel for semen into the female's cloaca

Prismatic calcification

buildup of excess calcium in the body

Lechithotrophy

little maternal input, nutrition -> yolk, oviparous

Matrotrophy

high maternal input, nutrition -> mother's reproductive track

Oviparity

describes organisms that produce eggs that develop and hatch outside the body of the mother

Trophonemata

long filaments extending from the uterine wall of some elasmobranchs that secrete a fluid that nourishes their embryos

Hair cells

The hairlike sensory receptors for sound, which are embedded in the basilar membrane of the cochlea.

Monobasic fins

one bone connecting the fins

Ganoid scales

diamond shaped scales, comprised of bone

Urohyal bone

median dermal bone

Postanal tail

posterior elongation of the body, extending past the anus

Dermal bone

bone that forms directly in the skin rather than from cartilage, process is called intramembranous ossification

Endochondral bone

bone development that occurs by replaying hyaline cartilage

Centrum

solid, central part of each vertebra that gives strength to the vertebral column

Gas bladder

an organ in fish that provides buoyancy and prevents sinking

Binomial Nomenclature

a system of naming species of living things by giving each a name composed of two parts, both using latin grammatical forms

Kingdom, Phylum, Class, Order, Family, Genus, Species

Linnean Ranks

Monophyletic group (clade)

a group of organisms that share a most common recent ancestor and include all its decendants

Paraphyletic group

a group that contains a common ancestor and some but not all of the descendants

Homology

any characteristic of biological organisms that derived from a common ancestor

Convergent evolution

organisms that are not closely related develop similar features independently

Hemichordate

phylum of marine invertebrates, closely related to both echinoderms and chordates

Pharyngeal arches

early embryonic structures found in developing embryos, bilateral tissues that grow from the cephalic part of the neural crest, develops into cartilage, bone, nerves, muscles, glands, and connective tissue

Dorsal Hollow Nerve Chord

unique structure found in chordates, hollow tube of nervoud tissue located along the dorsal side of the body, basis for central nervous system

Endostyle

organ found in chordate animals, assists in filter-feeding, it evolved into the thyroid, secretes mucus to trap food particles in water drawn into the pharynx

Cephalization

evolutionary trend in animals where special sense organs and nerve ganglia become concentrated towards the rostral end of the body

‘Haikouella’

chordate fossil

Splanchnocranium

portion of the cranium that is derived from pharyngeal arches, forms the supporting structure of the jaw and consists of cartilage and endochondral bone

Neural crest

will form things line bones and muscles in cranium, unique germ layer in vertebrates

Hox genes

genes that help organize the development of an animal

Perichondral bone

bone that forms around cartilage

Neural arch

encloses the canal that the spinal cord passes through

Devonian

geological period and system of the Paleozoic era

'Placoderms'

jawed fish, anterior of body covered in think boney shield

Tidal ventilation

allows organisms to breathe while feeding

Flow-through ventilation

water goes through the mouth and over its gills

Vestibular apparatus

the organs in your inner ear that sense information your body needs to maintain balance

Semicircular canals

act as detectors for angular acceleration in their respective planes

Mandibular arch

mandible, mastication muscles, trigeminal nerve, gives rise to malleus and incus bones. Plays a role in feeding a speech

Hyoid arch

The second branchial arch, which forms the styloid process, stapes of the ear, stylohyoid ligament, and part of the hyoid bone.

Palatoquadrate

dorsal component of the mandibular arch

Meckel's cartilage

Cartilage that forms within each side of mandibular arch and that disappears as bony mandible forms

Spiracle

small opening located along the side of the body through which air enters and leaves the body of many terrestrial arthropods

Pelvic fins

used for turning, balance, and stopping

Pectoral fins

navigate, stop, back up, and help orient the body when at rest

Epaxial musculature

dorsal muscles associated with the vertebrae, ribs, and base of the skull

Hypaxial musculature

lie ventral to the horizontal septum of the vertebrae

Squalimorphii

super order of cartilaginous fishes, lacking traits like anal fin, nictitating membrane, suborbital shelves in the cranium

Galeomorphii

superorder of sharks

Ceratotrichia

slender soft or stiff filaments of an elastic protein, supporting tissue of the fins

Placoid scales

they are scales that protect fish from predators, the reduce drag so they are able to swim faster and quieter

Viviparity

giving birth to live young

Yolk sac vivparity

eggs retained inside, low maternal input, but live birth

Histotrophy

Developing embryos absorb maternal secretions

Placental Viviparity

development of a placenta

Oophagy

occurs only in Lamniformes sharks; nutrition is provided by the mother to developing embryos within the uterus by continuing to ovulate new eggs that are then consumed by the embryos

Branchiostegal rays

a fanlike series of dermal bones on the underside of the skull, forming the floor of the gill chamber

Latimeria chalumnae

West Indian Ocean Coelacanth

Cosmoid scales

scales that consist of two basal layers of bone, a layer of dentine-like cosmine and an outer layer of vitrodentine or enamel-like substance

Pharyngeal jaws

jaws contained within an animals throat

Obligate air breather

respire entirely from atmosphere

Facultative air breather

breathe air when it is convenient but otherwise do not use lungs

Homocercal tail

A tail with the upper and lower lobes symmetrical and the vertebral column ending near the middle of the base, as in most telost fishes.

Premaxilla

Bony area of the upper jaw that includes the alveolar ridge for the incisors and the area immediately behind it.

Maxilla

upper jaw