Subclass Ostracodermi General characteristics: Had bony armor Were jawless
Had no paired appendages Had no vertebrae The major axis of support was
the notochord Had gill slits or gill pouches for breathing
Myxinidae - Hagfish Order: Myxiniformes Class: Myxini from “myx
-“ (Gr.) = slime
Not a big group; ~31-39 species in the world
Marine, temperate zones of the world, mainly on the continental shelves,
Gulfs of Mexico and Panama.
Found primarily in temperate latitudes from 60-1800 ft in depth
North America has two species
Myxine glutinose (Atlantic) 5-6 gill pouches,
one external pore
Bdellostoma stoutii (Pacific) 5-15 gill pouches
Jaws absent, no bones.
Body naked, eel-like.
Degenerate eyes.
1-16 pairs of external gill openings.
No paired fins, no dorsal fin.
Part of caudal fin extends onto dorsal surface.
Scavengers on invertebrates and others, e.g., netted fishes
Biting mouth bearing barbels.
Teeth only on tongue plus one on 'palate'.
Mucous pores in 2 ventrolateral lines, each line with about 70-200
glands containing mucous cells and thread cells – thought to be a protective
mechanism from predation by “clogging” gills of predators
Ovaries and testes in same individual but functionally non-hermaphroditic,
produce about 30 large yolky eggs No metamorphosis - young develop as miniature
adults
Only vertebrates with body fluids iso-osmotic with seawater – effectively
the same as salt-water invertebrates with a holonephric kidney
Circulatory system with several divided heart structures - cardinal,
caudal, portal, and brachial hearts
About 80 cm max length.
Used as food in Japan.
Skin is scaleless and supple – hides are processed into 'eel'
leather in Korea
Petromyzontidae - Lampreys Order: Petromyzontiformes from petr
- (Gr.) = stone + myz - (Gr.) = suck Class: Cephalaspidomorphi
Distribution mainly temperate zones of the world
Marine species anadromous
Eel-like, jawless fish with cartilaginous skeleton and notochord.
Pouch-like gills not supported by gill arches
No scales and no paired fins; 1-2 dorsal fins
Teeth on oral disc and tongue
Nasohypophyseal sac has an external opening only
Intestinal tract with spiral valve and cilia
Dorsal and ventral nerve roots separated
Sexes separate; eggs numerous (thousands), small and not yolky; parents
die after spawning
Radical metamorphosis of ammocoete larvae in freshwater
Members of Petromyzontinae have the highest number of chromosomes (164-168)
among vertebrates
Larvae max 10 cm, adults max 120 cm
Parasitic or non-parasitic, the latter restricted to freshwater
GNATHOSTOMES
Two major innovations make this group successful:
jaws developed from the first gill arch
paired appendages (fins)
These two characteristics allowed them to become predaceous jaws allowed
them to catch and consume prey
paired appendages gave fishes more maneuverability - fins add stability
and control
there is no good indication for the origin of appendages - one simply
the fin-fold theory
Gnathostomes developed into a number of clades:
Ancestral gnathostomes =>
Placoderms - extinct
Chondrichthyes
Acanthodians - extinct
Osteichthyes
Flourished in the late Devonian and early Silurian
Class Placodermi - armoured fishes An extinct group well-represented
in the fossil record
Name means “plate skin” because skin had dermal bone plates
much like Ostracoderms; however, placoderms had jaws and paired appendages
no evidence of vertebral column
had a notochord but no vertebral column
varied in size- some as large as 6m in length
well-represented in the Devonian Period - some were benthic while others
appeared to be more predaceous
CHONDRICHTHYES - CARTILAGENOUS FISHES
skeleton composed of calcified cartilage
bone is thought to be more primitive to cartilage
500-700 species; all marine
have jaws and paired appendages
have 5-7 external gill openings or gill slits and one reduced gill
called a spiracle or false gill
no swim bladder
internal fertilization
may be viviporous, oviporous, or ovoviviporous
Two Parental Clades for Chondrichthyes NOW ELEVATED TO CLASS
Class Elasmobranchii
the sharks, rays, and skates
~700 species
several gill openings
placoid type of scales
Elasmobranchii subdivided into two groups:
pleurotremata (“side hole”) - refers to location of gills on the side
of the head: sharks
hypsotremata (“below hole”) - refers to location of gills on the ventral
surface: rays and skates
gills of both groups ventilated by a double pump and by the spiracles
in some sharks ventilation requires a continuous movement for water
to pass over the gills
sharks lack a swim bladder; have an oil (squalene) produced by the
liver which acts as a density control device by adjusting overall body
density
Generalized Classification of Elasmobranchii:
Squalimorphs - spring and green dogfish sharks
~80 species
live in cold deep waters
Squalus acanthius - dogfish shark
Galeomorphs - contains most of the sharks
~250 species
all with five gill openings
dominant carnivores of shallow waters
hammerhead, great white, whale shark
Batoidia - skates and rays
~425 species
skates have pointed nose and lay eggs, rays give live birth
Squatinomorphii
~two species with depressiform body
pectoral fins do not fuse with the body
Genus Squatina - angel shark and monkfish
PRIMARY REPRODUCTIVE PATTERNS
Oviarous - egg layers
Ovoviviparous - live birth
during development the young are nourished by the yolk
when the egg is fertilized, it has a large yolk and the embryo develops
in the uterus while obtaining nutrient from the stored yolk
Viviarous - live birth
young receive nourishment from some type of placental attachment
nourishment comes from the mother’s blood, secretions, or other tissues
Family: Echinorhinidae - Bramble sharks Order: Squaliformes (bramble,
sleeper and dogfish sharks) Class: Elasmobranchii - sharks and rays
Large (3-4 m), wide-ranging, deepwater sharks in cold-temperate to
tropical seas.
Circumglobal distribution on continental and insular shelves and slopes
from 11 to 900 m, on or near the bottom.
Short-nosed, cylindrical sharks with no anal fin
Skin covered with coarse denticles or enlarged thorns
Feed on a variety of benthic and neritic fishes, including other sharks
as well as crabs, octopuses and squids
Thought to suck in their prey by suddenly expanding their mouths and
pharynxes when in range
Ovoviviparous and lack a yolksac placenta
Family: Ginglymostomatidae - Nurse sharks Order: Orectolobiformes (carpet
sharks) Class: Elasmobranchii (sharks and rays)
Marine, all oceans. Small to large sharks with nasoral grooves, short
to long barbels, small spiracles behind eyes.
Two spineless fins and an anal fin, the second dorsal origin well ahead
of the anal origin.
A short precaudal tail, much shorter than the head and the body.
Common, small to large, nocturnal, inshore bottom sharks with a circumglobal
distribution in subtropical and tropical waters, in depths from the intertidal
down to at least 70 m.
Cruise and clamber on the bottom with their mouths and barbels close
to the substrate while searching for food.
They use their short, small mouths and large mouth cavities as a bellows
to suck in their prey: bony fish, crabs, shrimps, lobsters, squids, octopuses,
corals, sea urchins, sea squirts.
Family: Sphyrnidae - Hammerhead, Bonnethead, and Scoophead sharks Order:
Carchariniformes (ground sharks) Class: Elasmobranchii (sharks and rays)
Marine, coastal; occasionally in brackish water.
Global (chiefly warm waters).
Head laterally expanded, with eyes and nasal openings much widely set
than in other sharks.
No spiracle.
A maximum length of 4.5 m was reported for Sphyrna tudes.
Feed on a wide variety of bony fish, elasmobranchs, cephalopods, crustaceans,
and other prey.
Family: Cetorhinidae - Basking sharks Order: Lamniformes (mackerel sharks)
Class: Elasmobranchii (sharks and rays)
Marine, all oceans, highly migratory.
Gill openings exceptionally large; gill rakers elongate, plankton feeders,
teeth reduced.
The tail is nearly symmetrical with keel on caudal peduncle.
Fifth gill opening in front of pectoral fin.
The family contains the world's second largest fish, reportedly reaching
1,520 cm TL.
Family: Lamnidae - Mackerel sharks, White sharks Order: Lamniformes
(mackerel sharks) Class: Elasmobranchii (sharks and rays)
Distribution: global. Large sharks with pointed snouts and spindle-shaped
bodies.
Large gill openings.
First dorsal fin large, high, erect and angular or somewhat rounded;
second dorsal and anal fins minute.
Caudal peduncle with a distinct keel; large teeth; fifth gill opening
in front of pectoral fin; spiracle sometimes absent.
Maximum length up to 6.4 m or more.
Fast swimming predators - some are man-eaters.
Ovoviviparous without a yolk-sac placenta but with uterine cannibalism.
Family: Squalidae - Dogfish sharks Order: Squaliformes (bramble, sleeper
and dogfish sharks) Class: Elasmobranchii (sharks and rays)
Atlantic, Indian and Pacific Oceans
No lateral teeth or barbels. Dorsal fin with or without spines
5 gill openings anterior to pectoral fin
Maximum length at 6.3 m, reported for Somniosus microcephalus
This family includes the smallest sharks in the world.
Family: Pristidae - Sawfishes Order: Pristiformes (sawfishes) Class:
Elasmobranchii (sharks and rays)
Atlantic, Indian, and Pacific Oceans.
Snout elongated into a long flat blade with teeth of uniform size deeply
embedded on each side.
No barbels. Head depressed with the body more or less resembling a
shark.
Two distinct dorsal fins.
Giant fishes of coastal waters, entering estuaries and ascending large
rivers for great distances. Used for food and regarded as exciting game
fishes because of their size. Although generally harmless to humans, their
large size and sawlike beak make them dangerous when hooked or speared.
Of the many nominal species only four appear to be valid.
Family: Anacanthobatidae - Smooth skates Order: Rajiformes (skates and
rays) Class: Elasmobranchii (sharks and rays)
Known from South Africa, Natal, and the tropical western Atlantic;
also from Taiwan.
A terminal filament of varying length arising from a small, bluntly
rounded protuberance at the tip of the snout.
Dorsal fins absent, but membranous caudal fin present. Five pairs of
small, ventral gill slits.
Dorsal and ventral surfaces of disc smooth, without dermal denticles.
Tail slender, a bit shorter than disc. Small skates of slope regions
in tropical/subtropical waters.
Family: Platyrhinidae - Thornbacks Order: Rajiformes (skates and rays)
Class: Elasmobranchii (sharks and rays)
Atlantic, Indian and Pacific Oceans.
Body form intermediate between that of a shark and a skate.
Tail stout, not well demarcated from body.
Dorsal fins 2; distinct.
Caudal fin present.
Denticles arranged in a row on dorsal midline.
No spine in tail.
Family: Rajidae - Skates Order: Rajiformes (skates and rays) Class:
Elasmobranchii (sharks and rays)
Benthic rays occurring in all oceans, from Arctic to Antarctic waters
and from shallow coastal shelves to abyssal regions; some species enter
brackish waters.
Disc quadrangular to rhomboidal.
Mouth transversed to arched, with numerous teeth.
Five pairs of ventral gill slits.
Tail very slender, with lateral folds, usually 2 reduced dorsal fins
and a reduced caudal fin.
Electric organs weak, developed from caudal muscles.
Skin prickly in most species, the prickles often in a row along midline
of dorsal.
Oviparous; eggs in a horny capsule with four long tips.
Skates feed on other benthic organisms. Skate wings are considered
good eating.
Family: Rhinobatidae - Guitarfishes Order: Rajiformes (skates and rays)
Class: Elasmobranchii (sharks and rays)
Atlantic, Indian and Pacific Oceans mostly in tropical coastal waters.
Body form intermediate between that of a shark and a skate.
Also called shovelnose sharks.
Numerous small, blunt teeth in jaws.
Two large dorsal fins; caudal fin well developed.
Denticles arranged in a row on dorsal midline.
No spine in tail.
They reach moderate to large size and are important commercial species
in many coastal nations.
Ovoviviparous.
Feed on bottom organisms, including molluscs and crustaceans, but will
also take small fishes.
Family: Dasyatidae - Sting rays Order: Myliobatiformes (eagle rays,
stingrays and mantas) Class: Elasmobranchii (sharks and rays)
Chiefly marine; also in brackish and freshwater - Atlantic, Indian
and Pacific Oceans.
Side of head continuous with anterior margin of pectoral fin.
Dorsal fin totally absent or indistinct, when present.
Disc about 1.2 times as broad as long.
No caudal fin.
Tail long and whip-like.
Most species with at least 1 long venomous spine on tail, which can
cause excruciating pain to humans.
Largest species to about 4m length or width.
Live-bearing (ovoviviparous).
Family: Mobulidae - Manta rays and devil rays Order: Myliobatiformes
(eagle rays, stingrays and mantas) Class: Elasmobranchii (sharks and rays)
Atlantic, Indian and Pacific Oceans.
Head differentiated from disc.
Eyes and spiracles on sides of head.
Mouth ventral in Mobula and terminal in Manta.
Size of gill openings almost the length of eye. Length of tail much
greater than disc. Some with spines.
Dorsal fin small. Caudal fin lacking. Three functional paired limbs.
The cephalic pair of fins aid in feeding and are said to be essentially
the anterior subdivision of the pectorals.
Some reach about 6.1 m and weigh over 1360 kg.
Class Holocephali
chimaeras or ratfish
~25 species
gills covered by an operculum
no placoid scales
Chimaeridae - Chimaeras or ratfishes Order: Chimaeriformes
Class: Holocephali
Atlantic, Pacific, and Indian oceans in temperate to tropical waters,
mostly below 200 m
Short and rounded snout
First dorsal fin erectile, with a strong spine; second dorsal fin long
and low
Diphycercal tail - vertebral column runs straight to the tip, dividing
the caudal fin symmetrically
Anal fin confluent with caudal fin in Hydrolagus ; separate in Chimaera
Feed on small fishes and bottom invertebrates
Males with head clasper
Oviparous; large tadpole-shaped egg capsules are deposited on substrate
Dorsal spine with associated poison gland, the venom of which hurts
humans
Family: Rhinochimaeridae - Longnose chimaeras Remark: Found at scattered localities worldwide in temperate and tropical seas, in 200 to more than 2,000 m depth. Long and pointed snout, lacking a hooklike process. First dorsal fin erectile, with a strong, mildly toxic spine; second dorsal fin long, low and not falcate. Diphycercal tail, i.e., the vertebral column is extending to the tip and divides the caudal fin symmetrically; caudal fin may be confluent with or separate from anal fin. Oviparous: egg-cases spindle-shaped, with broad filamentous horizontal flanges.
Family: Echinorhinidae - Bramble sharks Order: Squaliformes (bramble,
sleeper and dogfish sharks) Class: Elasmobranchii (sharks and rays) Large
(3-4 m), wide-ranging, deepwater sharks in cold-temperate to tropical seas.
Circumglobal distribution on continental and insular shelves and slopes
from 11 to 900 m, on or near the bottom. Short-nosed, cylindrical sharks
with no anal fin Two very small, spineless, posterior dorsal fins, the
first behind the pelvic origins
Skin covered with coarse denticles or enlarged thorns Feed on a variety
of benthic and neritic fishes, including other sharks, ling, hake, flatfishes,
lingcod, lizardfishes, rockfishes, topsmelt, herring, and elephantfishes,
as well as crabs, octopuses and squids Thought to suck in their prey by
suddenly expanding their mouths and pharynxes when in range Ovoviviparous
and lack a yolksac placenta
Family: Latimeriidae - Gombessa Order: Coelacanthiformes (coelacanths)
Class: Sarcopterygii (lobe-finned fishes)
South Africa? and Comoros archipelago.
Ovoviviparous livebearers which produce 19-59 eggs and about 5 young.
Eggs can attain a diameter of 9 cm. In the oviduct the young can reach
about 33 cm total length. Gestation period 13 month.
Adults with maximum length of 1.8 m.
Live on steep steep rocky shores, sheltering in caves during the day
(often in groups) and foraging singly over open substrates at night preferred
depth 180-220 m, temperature 16-23 C°.
Long-lived, slow-growing, epibenthic drift-predators of fish and squid
- main enemies are likely to be large sharks.
An inventory of all known specimens lists 171 specimens that have been
caught off the Comoros since 1952.
Family: Ceratodontidae Australian lungfish Order: Ceratodontiformes
(Australian lungfishes) Class: Sarcopterygii (lobe-finned fishes)
The family is restricted to Australia and once contained 7 species,
but all except one are now extinct.
Fossil records from northern New South Wales reveal that the genus
Neoceratodus has remained virtually unchanged for over 100 million years
- one of the oldest living vertebrate genera. The surviving species is
now confined to a small section of southern Queensland.
Differs from South American and African lungfishes in the paddle-like
shape of the pectoral and pelvic fins, in having only a single instead
of a double swim bladder, and in lacking the ability to aestivate (survive
with reduced metabolism in mucus cover) during dry spells.
Family: Lepidosirenidae - Aestivating lungfishes Order: Lepidosireniformes
(South American and African lungfishes) Class: Sarcopterygii (lobe-finned
fishes)
West Africa, Brazil and Paraguay, in slow-moving fresh waters and swamps.
Gill arches 5, gill clefts 4.
Very elongated body.
String-like pectorals and pelvis.
Has the ability to survive dry spells by aestivation (a state of reduced
metabolism) borrowed in a mud hole and enveloped in a mucus cocoon.
Family: Acipenseridae - Sturgeons Order: Acipenseriformes (sturgeons
and paddlefishes) Class: Actinopterygii (ray-finned fishes)
Cold to temperate waters of the Northern Hemisphere.
Anadromous or restricted to freshwater.
Body with 5 rows of scutes.
Mouth inferior and protractile; four barbels anterior to mouth.
Less than 50 gill rakers.
Adults toothless.
Large swim bladder.
Attain 4.2 m or longer.
Important for their meat and roe.
Nearly all species are endangered or threatened.
Family: Polyodontidae - Paddlefishes Order: Acipenseriformes (sturgeons
and paddlefishes) Class: Actinopterygii (ray-finned fishes)
China and United States.
Snout resembling a paddle and with minute barbels.
Body scaleless (naked) except for a few scales on caudal peduncle.
Heterocercal caudal fin.
Gill rakers long and numerous (hundreds) in the planktivorous Polyodon.
Minute teeth. Spiracle present. Operculum greatly extended posteriorly.
Mouth protrusible or nonprotrusible.
Two monotypic genera (Polyodon and Psephurus). Exhibited in public
aquaria and used for food. Both species are under threat.
Family: Lepisosteidae - Gars Order: Lepisosteiformes (gars) Class: Actinopterygii
(ray-finned fishes)
Chiefly freshwater, in brackish water occasionally; very rarely marine
from eastern North America (from southern Quebec) to Costa Rica; Cuba.
Body elongate; jaws elongated, with needlelike teeth.
Short heterocercal tail.
Heavily armored with ganoid scales.
Dorsal fin far down posterior with few dorsal rays.
Gular or interopercle absent and paired vomer.
Vascularized swim bladder allows aerial respiration. Vertebrae convex
anteriorly, concave posteriorly.
About 3 m maximum length.
Family: Amiidae - Bowfins Order: Amiiformes (bowfins) Class: Actinopterygii
(ray-finned fishes)
Distribution restricted to eastern North America.
Short heterocercal caudal fin.
Long dorsal fin base with about 48 dorsal rays.
Large median gular plate.
Swim bladder capable of respiratory function.
Pyloric caeca absent.
Maximum branchiostegal expansion and hyoid depression attained with
closed jaws.
About 90 cm maximum length.
Family: Muraenidae - Moray eels Order: Anguilliformes (eels and morays)
Class: Actinopterygii (ray-finned fishes)
Diverse group of eels with large mouths
with numerous teeth; often with fanglike (canine) teeth.
Dorsal fin origin usually before the gill openings; median fins confluent
with caudal fin; no pelvic and pectoral fins.
Gill openings as small roundish lateral openings.
Head with 1-3 lateral line pores; absent on body.
Scaleless.
Recorded maximum length 3.0 m.
Adults benthic, generally in shallow water among rocks and coral heads;
many species are more active at night and hide in holes and crevices during
the day.
Vicious reputation is undeserved, although some species will bite if
provoked.
Family: Catostomidae – Suckers Order: Cypriniformes (carps) Class: Actinopterygii
(ray-finned fishes)
Distribution China, northeast Siberia, North America.
Pharyngeal teeth a single row with at least 16 teeth.
Lips usually thick and fleshy with plicae or papillae.
Premaxilla and maxilla usually bordering upper jaw.
Exhibits tetraploidy.
About 1 m maximum length, usually below 60 cm.
Family: Cyprinidae Minnows or carps Order: Cypriniformes (carps) Class:
Actinopterygii (ray-finned fishes)
Distribution northern Canada to Mexico, Africa, and Eurasia.
Pharynx with 1-3 rows of teeth, each row with a maximum of 8 teeth.
Maximum length at least 2.5 m to probably 3 m in Catlocarpio siamensis;
many species less than 3 cm.
The family includes herbivores and predators.
Family: Cyprinodontidae – Killifishes Order: Cyprinodontiformes (rivulines,
killifishes and live bearers) Class: Actinopterygii (ray-finned fishes)
Chiefly freshwater and brackish; rarely coastal marine of southeastern
Canada to South America, Africa, Madagascar, southern Europe, and southern
Asia.
Egg-laying.
Males without gonopodium.
Pelvic bases relatively far apart.
Pelvic fins may be absent.
The first 2 dorsal radials with only 1 ray.
About 16 cm maximum length.
Family: Poeciliidae – Livebearers Order: Cyprinodontiformes (rivulines,
killifishes and live bearers) Class: Actinopterygii (ray-finned fishes)
Distribution low altitudes from eastern United States to northeastern
Argentina.
Anal fin with the first 3 rays unbranched.
Anterior anal fin rays in males form a gonopodium.
Fertilization internal - viviparous.
Some species with all-female individuals, their eggs capable of developing
when stimulated by the sperm of another species without fertilization.
Usually less than 18 cm maximum length.
Family: Centrarchidae – Sunfishes Order: Perciformes (perch-likes) Class:
Actinopterygii (ray-finned fishes)
Distribution North America.
Anal spines at least 3.
Pseudobranch small and hidden; branchiostegal rays 5-7; separate gill
membranes.
To about 83 cm maximum length (reported for Micropterus salmoides).
Mostly nest builders - nest building and guarding done by the male.
Valued as sports fish and used in physiological and ecological experiments.
Introduced into many areas outside native range.
Family: Cichlidae – Cichlids Order: Perciformes (perch-likes) Class:
Actinopterygii (ray-finned fishes)
Distribution: Central and South America, Texas (1 species), West Indies,
Africa, Madagascar, Syria, and coastal India - Some species widely introduced.
Body shape quite variable, mostly moderately deep and compressed.
A nostril on each side of head.
Interrupted lateral line; scales in lateral lines may be over 100,
usually 20-50.
Dorsal fin usually with 7-25 spines and 5-30 soft rays.
Spines in anal fin 3-15 (generally 3); soft rays 4-15 (a few with 30).
Colorful cichlids are reared as aquarium fish.
Breeding activities highly organized: Parental care in 3 forms: mouthbrooding,
substratebrooding, and substratebrooding of eggs then mouthbrooding of
young.
Family: Echeneidae – Remoras Order: Perciformes (perch-likes) Class:
Actinopterygii (ray-finned fishes)
Distribution: Atlantic, Indian and Pacific.
Elongate body, with the head flattened and bearing a sucking disc having
10-28 transverse movable lamina (disc said to have evolved from a spinous
dorsal fin).
Mandible jutted.
Scales small and cycloid.
Spines absent in dorsal and anal fins; about 18-40 soft rays each in
dorsal and anal fins.
No swim bladder.
Hitches to larger animals such as sharks, bony fishes, turtles or mammals
with the sucking disk - some species reportedly show considerable host
specificity.
Family: Gobiidae – Gobies Order: Perciformes (perch-likes) Class: Actinopterygii
(ray-finned fishes)
Chiefly marine and brackish, some species are catadromous.
Distribution: mostly tropical and subtropical areas.
The largest family of marine fishes (possibly > 2,000).
The smallest fishes in the world belong to this family.
Some species have symbiotic relationships with invertebrates (e.g.
shrimps) and others are known to remove ectoparasites from other fishes.
Many are popular aquarium fishes.
Family: Istiophoridae – Billfishes Order: Perciformes (perch-likes)
Class: Actinopterygii (ray-finned fishes)
Distribution: most tropical and subtropical waters.
Premaxilla and nasal bones produced, forming a spear-like bill or rostrum
with a rounded cross-section.
Dorsal fin extending over much of body length; sometimes resembling
a sail.
Maximum length 4 m.
Bill used for stunning prey fish.
Very popular as game fish.
Family: Moronidae - Temperate basses Order: Perciformes (perch-likes)
Class: Actinopterygii (ray-finned fishes)
In brackish and freshwaters and marine coastal areas of North America,
Australia, Atlantic with Mediterranean, and Pacific.
Two dorsal fins, the first with 8-10 spines and the second with one
spine and 10-13 soft rays; anal fin with 3 spines and 9-12 soft rays.
Two spines on operculum.
Seven branchiostegal rays; 25 vertebrae.
Large predators, up to 2 m length in Polyprion americanum.
Heterogenous group of freshwater and marine species.
Family: Percidae – Perches Order: Perciformes (perch-likes) Class: Actinopterygii
(ray-finned fishes)
Distribution: Northern Hemisphere.
Dorsal fins separate or narrowly joined (Zingel with dorsals broadly
united).
Anal spines 1 or 2, the second usually weak.
Pelvic fins thoracic; a single spine and 5 soft rays in the pelvic
fin.
Branchiostegal rays 5-8; separate from isthmus.
To 90 cm maximum length (reported for Stizostedion vitreum).
Some species enter estuaries.
Family: Scombridae - Mackerels, tunas, bonitos Order: Perciformes (perch-likes)
Class: Actinopterygii (ray-finned fishes)
Distribution: tropical and subtropical seas.
The 2 dorsal fins separate and depressible into grooves.
Finlets following anal and posterior dorsal fins.
Origin of anterior dorsal fin well behind the head.
Pectoral fins high on body and pelvic fins below pectorals, with 6
fin rays.
Gill membranes not united to isthmus.
Small cycloid scales present.
Two keels on slender caudal peduncle.
Thunnus and close relatives with a specialized vascular system for
heat exchange
Family: Aphrenodontidae - Pirate perches Order: Percopsiformes (trout-perches,
pirate perches and cavefishes) Class: Actinopterygii (ray-finned fishes)
Distributed throughout eastern United States.
Scales ctenoid; head scaly on sides.
Normal eyes.
Dorsal fin spines 3 or 4; soft rays 10 or 11.
Anal fin spines 2 or 3; soft rays 5-7.
Pelvic fin insertion subthoracic; pelvic rays 7.
Anus in juveniles immediately preceding anal fin, moving anteriorly
with growth.
About 13 cm maximum length.
Family: Bothidae - Lefteye flounders Order: Pleuronectiformes (flatfishes)
Class: Actinopterygii (ray-finned fishes)
Distribution: tropical and temperate Atlantic, Indian, and Pacific
oceans.
Both eyes on left side in most species.
Preopercle margin free and distinct.
No spines in fins; dorsal fin origin above or anterior to upper eye.
Dorsal and anal fins separate from caudal fin.
Branchiostegal membranes united.
Anus on blind side.
Egg yolk with a single oil globule.
Lefteye flounders are found in all tropical and temperate seas, and
several species are of commercial importance.
Family: Esocidae – Pikes Order: Salmoniformes (salmons, pikes and smelts)
Class: Actinopterygii (ray-finned fishes)
Distribution: Northern Hemishpere, colder parts of Eurasia and North
America.
Duckbill-like snout.
Forked caudal fin; caudal rays 40-50, usually 17 branched rays; no
spines.
Many small cycloid scales.
Complete lateral line with at least 8 pores in infraorbital canal.
Branchiostegal rays 9-20.
Nasals present.
To 1.8 m maximum length.
Pikes are voracious predators, feeding on a wide variety of fishes
and other vertebrates.
Family: Salmonidae – Salmonids Order: Salmoniformes (salmons, pikes
and smelts) Class: Actinopterygii (ray-finned fishes)
Distribution: Northern Hemisphere, but widely introduced in cold waters
for sports and aquaculture.
Many are anadromous, spending part of their life at sea, but returning
to freshwater where all species spawn in a gravel bed in rivers or streams;
most fish die after
spawning.
Small cycloid scales.
Gill membranes reaching far forward, detached from isthmus.
Adipose fin present.
Attains 1.5 m (maybe 2 m) maximum length.
Highly valuable in sport and commercial fisheries.
There is disagreement about the status of some species and genera.
Family: Ictaluridae - North American freshwater catfishes Order: Siluriformes
(catfish) Class: Actinopterygii (ray-finned fishes)
Distribution: North America from southern Canada to Guatemala.
Head with eight barbels: 2 nasal, 2 maxillary and 4 chin.
Scaleless.
A spine on anterior edge of dorsal (except in Pritella) and pectoral
fins.
Dorsal soft rays usually 6.
No palatine teeth.
About 1.6 m maximum length
Family: Syngnathidae - Pipefishes and seahorses Order: Syngnathiformes
(pipefishes and seahorses) Class: Actinopterygii (ray-finned fishes)
Mostly marine; some in brackish and fresh water.
Distribution: Atlantic, Indian, and Pacific Oceans (mostly in warm
temperate to tropical).
A series of bony rings encloses elongate body.
Adults of some species may lack dorsal, anal, and pectoral fins.
Pelvic fins lacking; s ome without caudal fin; caudal peduncle may
be prehensile.
Very small gill openings.
Kidney unpaired (right side) and lacking glomerulus.
About 60 cm maximum length.
Some very colorful.
Usually limited to shallow water.
Family: Tetraodontidae – Puffers Order: Tetraodontiformes (puffers and
filefishes) Class: Actinopterygii (ray-finned fishes)
Chiefly marine - many going into and inhabiting brackish and freshwater.
Distribution: tropical and subtropical areas of Atlantic, Indian and
Pacific.
Naked or with short prickles in belly.
Jaw teeth fused but separated by a median suture in each jaw, giving
rise to 4 fused teeth.
Opposite dentaries and premaxillaries separate at midline.
Usually 7-18 dorsal soft rays; anal soft rays usually 7-18.
Attains 90 cm maximum length.
Some puffers contain tetraodotoxin, especially in the viscera; in the
gonads of some during spawning season. European Community legislation prohibits
trading with puffer fish products.
Most species are oviparous but some are viviparous (~1%) or ovoviviparous
those that are viviparous are primarily guppies, top minnows, gambusia
eggs are mesolecithal (moderate amount of yolk) or megalecithel (heavily
yolked) and
GENERALIZED FISH ANATOMY
Greatest depth and width about 1/3 back from mouth
Mouth shape and position highly variable
Operculum (bony flap) covers gills - water enters mouth, passes through
pharynx and across gills, exits through opercular opening
Tail terminates with bony or cartelagenous rays
Fins represented by single median caudal, dorsal (1-3), anal and adipose
fins; paired pectoral and pelvic fins - fin location, size, and shape highly
variable
Jaws developed from 1st and 2nd gill arches
RESPIRATORY SYSTEM
Gills line pouches in Agnathans but lie in bands in chondrychthyes
and bony fishes; supported by gill bars branching from expanded pharynx
through to outside operculum
accessory breathing organs include:
touch through tactile receptors on body surface
taste and smell both by molecular receptors in mouth, nasal epitheliumhearing dependent upon membraneous labyrinth
- choane secondary pouches on each side of the face not associate with the pharynx
- acoustical/lateral line system receptor system with asymmetrical hairlike protrusions - inhibition or stimulus of nerve endings dependent on direction of movement of hair cell capsule; very sensitive to fluid movement
sight well developed with size of eye directly related to depth and loss of light intensity
- thin membranous tubes and sacs in rough 3-planar arrangement of semicircular canals which sense motion and maintain balance
- Webberian ossicles associated with middle ear used to maintain balance - serves as an indicator of age
electric organs modified muscle cells capable of creating electric potential, electric current discharge or light impulse to stun prey or scare away predators - Ampullae of Lorenzini to detect electrical fields
- deep sea fishes often with chemoluminescent organs to generate their own light
- lens with bulge for better forward and upward vision
- also with increased refractive index for increased light gathering capabilities
- limited accommodation by moving the lens closer to or away from retina
- some species with partitioning of the lens to vary direction/observation such as air/water
- tapetum lucidum present behind retina of sharks to function like a mirror