Fish Morphology

Phylum Chordata Subphylum Vertebrata Class Agnatha Class Chondrichthyes Class Osteichthyes Class Amphibia Class Reptilia Class Aves Class Mammalia Classification Scheme of the Vertebrates

Chordate Characteristics

Placoderm ( ) lamprey & hagfish Ostracoderm (510-=350 mybp) Osteichthyes (395) Chondrichthyes (370) (360)

Jaw Development agnathostome gnathostome 1 st appeared 400 mya

Basic Anatomy Class Agnatha Possess medial nostril, medial fins, notocord rather than vertebral column 7 or more pr gill pouches present Light sensitive pineal eye Fertilization external Cartilaginous skeleton Lack jaws, paired fins, scales GI track w/out stomach Lampreys and hagfish 100 species

Class Agnatha Lamprey ammocoetes

Class Agnatha Hagfish

Basic Anatomy Class Chondrichthyes Sharks, skates, rays

Basic Anatomy Class Chondrichthyes Posses jaws with teeth, cartilaginous skeleton, paired fins Scales (denticles) have same origin and composition as teeth Possesses 5-7 gills Spiral valve intestine Ureoosmotic strategy Electroreception Lateral line No swim bladder Heterocercal tail Relatively unchanged (480 mybp) Sharks, skates, rays

Basic Anatomy

Class Osteichthyes

Basic Anatomy Class Osteichthyes Posses jaws with teeth, bony skeleton, paired fins 4 paired gill arches covered by operculum Intestine- simple, no spiral valve Swim bladder Lateral line Homocercal tail Scales- cycloid, ctenoid

Basic Anatomy bony fish

anus Internal Anatomy

Common Measurements

Basic Anatomy Latimeria Swim bladder modified to lungs Paired appendages May have given rise to terrestrial tetrapods Bony head Scales and teeth

General Life Style Categories a.pelagic cruisers 1.occurring in water column far away from the bottom (benthic) environment 2.often referred to as "blue water" 3.includes tuna, billfish, blue sharks, mackerel sharks (great whites and mako sharks) Fish Adaptations and Life Styles

b.demersal 1.bottom-associated fishes, but not usually sitting on the bottom 2.rely on the benthic environment as a source of food, place to reproduce, and/or place of refuge, etc. 3.includes most reef fishes (e.g., butterfly fishes, surgeon fishes, wrasses, parrot fishes, etc.)

c.benthic 1.bottom-dwelling fishes that spend the majority of time sitting on the bottom 2.includes flatfishes, lizard fishes, many scorpion fishes, many hawkfishes, gobies, etc.

tuna 1 ) fusiform a) = torpedo-shaped b) allows minimal drag while swimming c) best shape for a pelagic cruise Body shape

2)compressed a)laterally flattened (e.g., butterflyfishes & surgeonfishes) b)allows for maneuverability in surge environments c)useful for demersal fishes that hover above the reef d)exception seen in flatfishes that lie on one side of the body as benthic fishes

3)elongated or attenuated a)long body (e.g., trumpetfish, cornetfish, eels) b)seen in demersal fish that either hover motionless in the water) c)seen also in benthic fishes (e.g., eels) that hide in holes in the reef

4)depressed a)dorso-ventrally flattened (e.g., frogfishes, scorpionfishes & gobies) b)broad ventral surface facilitates resting on the bottom c)seen in many benthic fishes

Body Coloration 1)source of color a)pigment color - chromatophores for yellows, reds, oranges, browns, & blacks b)structural color - iridophores (reflection) & light refraction for blues, silvers, & rainbows

2)patterns a)countershading 1)dark blue or black dorsally, white or silvery ventrally 2)results in blue water "camouflage“ 3)observed most frequently in pelagic cruisers

b)camouflage 1)matching the background coloration 2)usually involves having irregular dark blotches and spots 3)typically seen in benthic fishes, especially benthic ambush predators (e.g., frogfishes, gobies, & many scorpionfishes) 4)some fishes (e.g., flatfishes) may exhibit rapid color changes in response to different backgrounds

b)camouflage 5) matching downwelling light Cookie cutter shark Hatchet fish

c)disruptive coloration 1)color pattern breaks up the silhouette of the fish 2)may involve dark bars across the eye and tail region 3)seen in many demersal fishes such as butterfly fishes

d)bars and stripes 1)bars are vertical (e.g., manini) 2)stripes are horizontal (e.g., ta'ape) 3)seen frequently in schooling demersal fishes 4)may confuse potential predators by making it difficult to select individual prey from the school

e)misdirection 1)false eye spots, etc. 2)observed in many demersal butterfly fishes

f)advertising coloration 1)bright, obvious color patterns 2)possible functions a)advertising a cleaning station (e.g., cleaner wrasses) b)advertising a warning (e.g., nohu) c)advertising for mates (e.g., male parrotfishes) Hawaiian cleaner wrasse Nohu

g)mimicry 1)imitating other creatures 2)seen in a few demersal and benthic fishes 3)examples a)blenny (Aspidontus taeniatus) mimics cleaner wrasses b)shortnose wrasse mimics Potter's angel which sports a defensive spine

g)mimicry 4)leafy sea dragon (Australia)

h)uniform red coloration 1)most often observed in deep-dwelling or night active demersal fishes 2)examples include opakapaka, oweoweo, menpachi, & squirrelfishes

i)noctural versus diurnal color changes j)male versus female color differences k)juvenile versus adult color differences Bluehead wrasse Dragon wrasse Stoplight parrotfish

Fish locomotion

T he source of propulsion for virtually all fish comes from: 1.Undulation of the body 2.Paired Fins: Pectoral Pelvic 3.Unpaired Fins: Caudal Dorsal Anal 4.A combination of the above Types of Fins

Anguilliform swimming (Undulation)

Dorsal & Anal Fin Propulsion

Anal Fin Propulsion Black ghost knifefish

Pectoral Fin Propulsion

Dorsal fin Bowfin Sea horse Knifefish

Pectoral Fin Frogfish

Walking catfish

Mudskipper

Sphere Disk teardrop Laminar flow and turbulence Hydrodynamics: Effects of shape on drag

Slowest Fish Ewa Blenny 0.5 mph

43.4 mph leaping 68 mph, leaping Blue-fin tuna Sailfin Fastest Fish

Tuna- long distance swimmer Snapper- short bursts

Countercurrent Exchange

Respiratory and Circulatory System

Ram Jet Ventilation

Buccal Pump Ventilation

Feeding Behavior Suction feeding Slingjaw wrasse

Inside lateral line canal

Swim bladder Large liver and heterocercal tail Fish adaptation to buoyancy in water Buoyancy Compensator Device (BCD)

Physostomous Gas Bladder air

Rete mirable Physoclist gas bladder

Missing in fish that swim fast or change depth rapidly (Tuna) Benthic fish (blennies, hawkfish, stonefish…) Sharks, skates, rays Deep water fish

Osmoregulation- the control of the concentration of body fluids. Diffusion- movement of substance from an area of greater concentration to an area of lower concentration Osmosis- diffusion of water through a semipermeable membrane

Marine Fish: hypoosmotic H 2 O continually leaves body continually drinks seawater excretes salt through gills produces small amts of dilute urine Less salt than external environment

Freshwater Fish: hyperosmotic H 2 O continually enters body does not drinks water produces large amts of dilute urine More salt than external environment

Shark and Coelacanth: ureoosmotic Maintains high levels of urea and TMAO in blood excretes salt through rectal gland coelacanth

Hagfish: ionosmotic nonregulator Seawater concentration = internal concentration

Osmolarity- measure of total solutes(dissolved particles) IonsFW m osmol/l SW m osmol/l Na+1470 Cl-1550 Ca++ variable10 Total Osmolarity in Freshwater and Saltwater

HabitatNa + Cl - Urea seawatersw hagfish (Myxine)sw lampreyfw12096 Goldfish (Carassius)fw Toadfish (Opsanus)sw160 Crab-eating frog (Rana)sw Dogfishsw freshwater rayfw150149<1 coelacanthsw

Sensory Systems 1.vision 2.hearing – inner ear; swim bladder amplifies in some fish 3.olfaction – olfactory sacs; taste buds 4.lateral lines of fish – detect vibrations in the water 5.ampullae of Lorenzini (sharks and rays) – sensitive to electric currents 6.geomagnetic sensory system (long distance migration- tuna)

Migration 1.Anadromous- salmon a)can return to the same stream in which they hatched b)may use land features, currents, salinity, temperature, the sun or magnetic field to get close to land c)sense of smell d)die after spawning e)young return to the sea 2. catadromous –freshwater eels 3. Extensive migration-anatomical basis for magnetotaxis -- magnitite