[14.1] Fishes

Fishes Fishes Group of aquatic limbless vertebrates, breathing mainly by means of gills, with streamlined bodies and fins and with the body covered in scales (in bony fishes), and comprising the Chondrichthyes (cartilaginous fishes) and the Osteichthyes (bony fishes). The Agnatha are also sometimes called fishes Actinopterygii The ray-finned fishes, a subclass of bony fishes (Osteichthyes) which includes all extant bony fishes except the lungfishes (Dipnoi) and the coelacanth Agnatha Taxon of primitive jawless verte3brates, including the lampreys (Monorhina), hagfishes (Diplorhina) and their extinct relatives Ammocoete Larva Larva of lamprey Anadromous Fishes which migrate from salt to fresh water annually Dorsal aorta Major artery carrying oxygenated blood to the rest of the body in vertebrates and cephalochordates. Aortic arch Paired arteries in vertebrate embryos, which connect dorsal and ventral arteries, running between gill slits on either side Appendicular A skeleton of the appendages skeleton Barbel A slender, external process on the jaw or other part of the head of certain fishes Chondrichthyes A class of fishes known from the Devonian to the present day, commonly known as the cartilaginous fishes, having a cartilageous skeleton, spiral valve in the gut, and no lungs or air bladder, and including the rays, skates, and sharks Coelcanth Members of an order of fish that includes the oldest living lineage of Sarcopterygii (lobe-finned fish + tetrapods) Cupula Jelly-like cup over a group of hair cells (a neuromast) in acoustic-lateralis system of fish and amphibians and vestibular system of mammals Cranium The skull, more particularly that part enclosing the brain Dentine Hard elastic substance, also known as ivoery, with same constituents as bone (collagen and calcium salts), consistuting the interior hard part of vertebrate teeth and outer layer of denticles and dermal bone Diphycercal tail With a caudal fin in which the vertebral column runs straight to tip, dividing the fin symmetrically Ectodermal Plate-like ectodermal thickenings placodes Euryhaline Marine organisms adaptable to a wide range of salinity Fusiform Spindle-shaped, tapering gradually at both ends (torpedo-like) Gas Gland Glandular portion of air bladder of certain fishes which secrets gas into the bladder Gnathostomata The jawed vertebrates, a subphylum of Chordata comprising the fishes, amphibians, reptiles, birds, and mammals Heterocercal tail Having vertebral column terminating in upper lobe of tail fin, which is usually larger than lower lobe, as in dogfish and other sharks Homocercal tail Type of tail fin in which vertebral column ends before it, and the upper and lower lobes are more-or-less equal Hyperosmotic Having higher salt concentration than the surroundings Hyposmotic Having a lower salt concentration than the surroundings Isoosmotic Having the same concentration of salts as the environment Keratin Fibrous protein rich in cysteine, chief material in horn, hair, nails, and upper flaky layer of skin Lingual cartilage Cartilage pertaining to tongue Lungfish Lobe-finned bony airbreathing fish of the subclass Dipnoi Myxini Hagfishes (also class Agnatha) Neural Arch Arch on the dorsal surface of vertebra for passage of the spinal cord Neural Crest Ridge of ectoderm that forms above the neural tube during early embryogenesis in vertebrates. The cells of the neural crest migrate to form a variety of structures. Neuromast A group of hair cells (sensory cells) comprising a sensory unit of the acoustic-lateralis system in fishes and some amphibians Nostril Exterior opening of the nose (also nares) Operculum Gill cove in fishes Ovale A part of a swim bladder which reabsorbs gas into blood Pectoral fin The fin on the side of body of fish Pectoral Girdle In vertebrates, a skeletal support in the shoulder region for attachment of fore-fins or forelimbs, made up of a hoop of cartilages or bones Pelvic fin Paired fins on underside of body of fish, representing the hindlimbs of land vertebrates Pelvic Girdle In vertebrates, a skeletal support in the hip portion for attachment of hind-finds or hindlimbs, made of a hoop of cartilages or bones Physoclistous fish Having no channel connecting swim bladder and digestive tract, as in most telosts Physostomous fish Swim bladder connected to the GI via pneumatic duct Pneumatic duct Connects swim bladder and GI tract Protochordates Group of animals comprising the hemichordates, urochordates, and cephalochordates, having gill slits, a dorsal hollow central nervous system, a persistent notochord, and a postanal tail Rete mirabile Small dense network of mainly arterial blood vessels in various organs of some vertebrates Rostum Beak-like structure (snout) of sharks Sarcopterygii A group of mostly extinct bony fishes having fleshy fins and nostrils opening into the mouth, comprising the lungfishes and the crossopterygians Swimbladder A gas-filled sac in body cavity of most teleost fishes, developed as an outgrowth of the alimentary canal, and which is an aid to buoyancy Tongue Movable and protractible organ on floor of mouth Fishes: Notochord with muscles attached; 2+  Early Vertebrate endoskeleton, exoskeleton, mainly Ca Introduction & **SPECIES POINT** Early vertebrates BIGGER protochordates  Musculoskeletal modifications o Living endoskeleton as framework for body & internal support structure o Segmented body muscles  W-shaped vertebrate  Arrows pointing @ myomeres (greater muscle contration, enabling longer bodies) o Increased musculature of gills  pump 2 O to get gas  Physiological modifications o Respiratory/circulatory systems mod to support large size/active lifestyle (metab. Dmd) o Pharynx mod into a muscular pump  pass water across internal gills; chambered heart to pump blood  Sensory system modifications [5] o Active, predatory life  new sensory/motor/integrated controls to locate/capture food [distance reception]  Sophisticated Eyes  Pressure Receptors inner ears (equil/sound)  Chemical Receptors olfactory (smell) organs  Lateral-line Receptors vibrations in water  Electrical Receptors ampullary organs o Neural Crest (ectodermal cells lying along embryonic neural tube  Crainum & Dentine 9teeth) [vert only] o Ectodermal Placodes plate-like ectodermal thickenings [vert only] Subphylum Vertebrata Maxini – Hagfish poor fossil record, changed little over milofy,  3 pairs of barbels around mouth  Eyes blind, good chemreceptors; no lateral-line system  1-14 gill openings, & pores (can breathe while feeding, through skin)  Caudal fin [tail], but no paired/dorsal fins  Nostril (connected to pharynx) used for water intake  Separate internal gill openings  Cranium underdeveloped; Vertebra