Primitive Fish Orders

Amphioxiforms

Amphioxiforms

LANCELETES

→ nonvertebrate

No cranium complex (Acranniates)

No cerebral, heart, respiration strucutres hemoglobin, red blood cells

25 gonands

one epidermal layer

PREY:

→ mostly diatoms and small food items

→ feed via cilla that transport water throuhg mucus mouth and pharnyx

Amphioxiforms

what order is the sister group to all verebrates

Myxiniformes

Order of Hagfish

→ Non-vertebrate

→ sister group to vertebrates and the basal craniate taxon

→ Stenohaline

→ Isomotic blood w/ the salinity of the surrounding water

→ Anatomy:

• four rudimentary hearts

→ Oxygen uptake

• water uptake through nostrils and run pass gills

• Capillary beds at skin: contribute to cutaneous respiration; aids in forgaging behavior

→ metabolism:

• low basal metabolic rates→ advantageous for deep sea environments, where prey encounters are low

→ Digestive System:

• Lack a true stomach

• Intestine begins at the pharynx and ends at anus w/ anterior muscular division

• Cloacal region

→ Sensory system:

• Photosensitive receptors: DERIVED characteristic

• Barbels: find food via touch and olfaction

Variable lymphocyte receptors

primitive proteins that respond to infectious agents; found in Myxiniformes and Petromyzontiformes

stenohaline

organism with a narrow range of salinity tolerance

ex: Myxiniformes

Petromyzontiformes

order of LAMPREYS

Anatomy:

→ Notochord supported by primitive vertebrate made of cartilage, lacks a constructed vertebrate

→ Elongated dorsal fin

→ Single Nostril

→ Separate dorsal and ventral roots of nerves

→ “Open” Circulatory system: sinuses connecting arterial and venous system in the brachial region help in gas exchange

largest diploid chromosome of any vertebrate: 140-170

Ammocete

larval stage of petromyzontiformes, characterized by a blind toothless stage.

→ burrows in bed of silty streams or rivers

→ head protrudes from the bottom and filter feeds through pharnyx produced muscus the

Gnathastomes

unranked taxonomic order of jawed verebrates

Cartilaginous skeleton

ceratotrichial fins

spiral valve intestine

oil-filled liver, instead of gas bladder

no larval stage

sutureless skull

male intromittent organs

multiple gill slits

Chondrichthyans Characteristics

Subclass Holocephali

Type of Chondrichthyan containing superorder holocephalimorpha with one extant order: chimaeriformes

Chimaeriformes

Order of the modern Chimaera

Anatomy:

→ Upper Jaws immovably attached to braincase

→ Denticles, Placoid Scales along the midline of the back, naked rest of the way

→ Single gill flap that cover four internal gill openings

→ Leptocercal caudal fin

Teeth:

→ 3 pairs of hypermineralized toothplates

Reproduction:

→ oviparous

Cartilaginous skeleton

Placoid Scales

Internal Fertilization

Replacement dentition

Multiple gill slits

Calcified skeleton

Calcified verbal Centra

Sutureless skull

Upper Jaw of Palaoquadtre cartilage, free from braincase

Unsegmented certotrichia

Oil livers

Spiral valve intestine

soft fin rays

Spiracle

Characteristics of SUBDIVSION ELASMOBRANCHI

Spiracle

first functional gill arch supported by the hyoid bone in Elasmobranchs

Myxoptergia

intromittent male sex organs on Chondrithyes

order heterodontiformes

order of bullhead and horn sharks

reproduction: oviparous

dorsal fin: 2, spine in frontal dorsal fin

Anal fin: Present

teeth: sharp front teeth, flat rounded back teeth

Orectolobiforms

order of carpet, blind, zebra, nurse, whale, and wobbegongs sharks

dorsal fins: 2

Gill slits: five with fifth overlapping the fourth

anal fin: present

Lamniformes

Order of mackerel sharks

large plegaic sharks

Dorsal fin: 2

Anal fin: present

reproduction: moslty ovoviviparous; eggs fertilized and hatched internally

→ evidence of oophagy occurring in families of Tiger Sharks

Some families capable of countercurrent exchange to maintain body heat

Carcharhiniformes

order of ground sharks

40% of all shark species

dorsal fine: 1

Reprodction: (mostly) viviparous

Anala fin: present

Carcharhinus leucas

species of Carcharinifromes capable of entering into FW peridoically

Hexanchiformes

order of frilled and cow sharks

dorsal fin: 1

gill slits: 6-7

reproduction: ovovivparous

Deepwater dwelling, well over 2km

Echinorhiniformes

order of bramble sharks

dorsal fin: 2

anal fin: absent

reproduction: ovovivparous

Large placoid scales all over body

Squaliformes

order of dogfish, gulper, sleeper, and kitefins

dorsal fin: 2

anal fin: Absent

Reproduction: unkown, slow maturation period

Squalamine production in liver has antibacterial properties used in cancer treatments

Squatiformes

order of angel sharks

flattened bodies, pectoreal and pelvic fins held horzonatally

dorsal fins: 2

reproduction: oboviviparous

Squalus acanthias

spiny dog fish

Prisitiophoriformes

order of saw sharks

dorsal: 5 fins

anal fin: absent

gill slits: 5-6

barbels for feeding

Batoidea

subdivision of skates and rays

→ ventral gill openings

→ anterior edge of enlarged pectoral fin attached to side of head

→ anal fin always absent

→ enlarged dorsal spiracles for water intake

Torpendiniforms

Order of electric rays and numb fishes

59 species

produce electric discharge from 8-220 volts

Pristiformes

Order of Sawfishes

7 marine and FW species

Respiration:

→ two large spiracles

→ ventral gills

Dorsal Fin: 2

Reproduction: ovoviviparous

No barbels

Fused pelvic fin

Rajiformes

ORder of skates, bowmouth guitarfishes, guitar fishes

dorsal fin: 2

large pectoral fins

285 marine species

Myliobatiforms

stingrays, butterfly rays, and eagle rays

183 species, marine and FW

reproduction: ovoviviparous

no dorsal fins

Barbel on sting ray: modified placoid scale

Grade Teleostomi

Contains all bony fishes

Includes Classes Sacropterygii and Actinopterygii

Class Sacropterygii

Lobed fined fishes

basal group to all bony fishes

contains order Colecanthiforms and order Ceratdoniformes

Coelacanthiforms

Order of Colecanths

Anatomy:

→ Uncsontricted and unossified modified notochord

→ fleshy lobed, paired and median fins

→ Diphyceral tail

→ thick bony scales

→ Gular plates on lower jaws

→ Thin bony layer vertebral spines and fin rays

→ No lungs

→ Fatfilled gas bladder

Reproduction: ovoviviparous; small clutch size, late maturation

→ Highly electrosenestive through rostral organs: series of pits and tubes in the snout that detects weak electrical currents

Ceratodonitoformes

Order of Lungfishes

apart of subclass Diponi

Anatomy:

→ Lungs and gills

→ Teeth not atttached to jaw margin, only occur on interior bone.

→ contain toothplates

All extant families are FW

Estivation

state of dormany Ceratodontiformes enter during dry summer months

→ construction of an underground mud cocoon when ponds dry up where they rely enteriely on air breathing

→ heart rate drops

→ body proteins are metabolzied and rapid weight loss occurs `

Class Actinopterygii

Latimeria chalumnae

living specimens of coelacanth discovered in 1938

Subclass Cladista

subclass and basal group of Actinopterygii

contains order POlypteriformes

gular plate

ventral bony plate that lies between the two lower jaws, or in the anerior third of the space between lower jaws(bowfin)

→ found in elopiodae, colecathiformes, subclass cladista

Polypteriformes

order of bichirs and reedfishes

16 species of freshwater fish

→ Bichirs:

→ 5-18 dorsal finlets; vertical spines attached to horizontal rays

→ few chromosomes

→ 34 gill arches

→ obgliate air breathers; recoil aspiration

Acipenseriformes

order of Acipenseridae and Polydontidae

apart of subclass Chondrostei

Acipenseridae

Family of Sturgeon

Anatomy:

→ Heterocercal tail

→ dorsal fin: 1

→ 5 rows of ganoid scutes

→ largley cartilaginous endoskelton

→ minute ossifications on body

→ protrusible mouth

→ barbels

→ spiracle

Reproduction:

→ all spawn in FW, leading to striclty FW species and anadromous species

→ high fecundity, but slow reproduction rates

Polydontidae

family of paddlefish

2 extant species

Anatomy:

→ heterocercal tail

→ unrestricted notochord

→ Cartilaginous skeleton w/ osffiied headbones

→ two small barbels

→ no scutes or scales

Behavior:

→ pelagic feeders on zooplankton and fish

Sensory organ:

→ Rostral paddle: contains electroreceptors(Ampullae of Lorenzi) used to detect prey

Class Neopterygi

Class of Lepiosoteriformes, Amiiformes, and all Teleosts

Lepisosteriformes

Order of Gar

Anatomy:

→ Ossified skeleton

→ constricted notochord

→ vertebral centra: opisthoceolous arrangement

→ ganoid scales

→ abbreviated heterocercal tail

→ no electroreception tecnqhiues

apart of subclass neopterygi

Amiiformes

order of bowfins

primitive features:

→ abbreviated heterocercal tail

→ spiral valve intestine

→ gular plate on underside of head

Derived features:

→ vertebrate

→ cycloid scales

→ no electroreception

Anatomy:

→ one long dorsal fin used to swim through undulation

Amia calva

One species of of the order amiiformes