Chapter 6 - Major Radiation of Fishes

Question 1

Osteichthyes

Answer 1

• Endochondrial bone - bone that develops from cartilage

- Operculum - bony gill covering that prevents backflow

Question 2

Synapomorphies of Actinopterygii

Answer 2

• Parallel arrays of closely packed radial bones support the base of the fins
• Single dorsal fin
• Scales composed of ganoine (glassy, multilayered, mineralized tissue)

Question 3

Order Polypteriformes - Birchir and Reedfish

Answer 3

• The most basal lineage of extant Actinopterygii
• Elongate, heavily armored fishes from Africa
• Flag-like dorsal finlets with spines
• Fleshy bases of pectoral fins
• Modified heterocercal tail
• Ganoid scales - shiny, enamol-like surface
• Well-ossified skeleton (ossify - to turn into bone)
• Paired ventral lungs

Question 4

Clade Actinopteri

Answer 4

• Includes all actinopterygii, except the order Polypteriformes
• Synapomorphy for clade
  
  • Swim bladder derived from lung

Question 5

Order Acipenserformes - Derived Characters

Answer 5

• Endochondrial bone absent

Question 6

Order Acipenserformes - Family Acipenseridae (Sturgeons)

Answer 6

• Large, active benthic fish
• Teeth absent in adults
• Five rows of enlarged armor-like scales along the body
• Reduced dermal skeleton
• Heterocercal tail armored with specialized series of scales
• Protrusible jaws

Question 7

Order Acipenserformes - Family Polyondontidae (Paddlefish)

Answer 7

• Even greater reduction of dermal skeleton

- Greatly elongated and flattened rostrum

Question 8

Synapomorphies of Neopterygians

Answer 8

• Upper pharyngeal teeth consolidated into tooth bearing plates
• Abbreviated heterocercal tail

Question 9

Primitive Neopterygians - Order Lepisosteiformes (Gar)

Answer 9

• Elongated jaws
• Thick armor
• Needlelike teeth

Question 10

Primitive Neopterygians - Order Amiiformes (Bowfin)

Answer 10

• Single species Amia calva
• Cycloid scales - thin, pliable scales formed of a thin sheet of bone-like material and underlying tissue
• Mobile maxilla (upper jaw)

Question 11

Synapomorphies of Telostei

Answer 11

• Premaxilla mobile allows for protrusible jaw and greater suction
• Powerful movable pharyngeal jaws
• Homocercal tail - symmetrical and flexible tail that allows the fish to swim horizontally without using its paired fins
• More diverse paired fins
• Uroneaural - modified posterior neural arches that support the dorsal side
• Thin-scaled or lack scales entirely

Question 12

Clade Osteoglossomorpha

Answer 12

• Found in tropical freshwaters

- Synapomorphy - Well developed teeth on the parasphenoid (one of the bones comprising the roof of the mouth)

Question 13

Clade Elopomorpha

Answer 13

• Leptocephalus larva - specialized larva that are adrift currents for a long time
• Most are eel-like and marine

Question 14

Clade Clupeomorpha

Answer 14

• Specialized mouth and gill straining apparatus for feeding on plankton
• Silvery scales
• Mostly marine schooling fish

Question 15

Clade Euteleostei

Answer 15

• Vast majority of extant teleost are in the clade Euteleostei
• Nuptial tubercles - structures located on the head, body, or fins that are made of epidermal cells that helps the contact between males and females during mating by providing friction

Question 16

Superorder Ostariophysi - Weberian Apparatus

Answer 16

Structure composed of small bones called ossicles (ear) that connects the swim bladder to the inner ear

Question 17

Superorder Ostariophysi - Alarm Substance

Answer 17

Pheromone that is released into the water when the skin is damaged thus causing a fright reaction by nearby members

Question 18

Superorder Ostariophysi - Adipose Fin

Answer 18

Small, fleshy, rayless fin found posterior to the dorsal fin

Question 19

Clade Neognathi

Answer 19

• Synapomorphy
• Increased contact of the first vertebrae with the skull bone
• Most basal lineage is the family salmonidae (salmon)

Question 20

Clade Acanthopterygii - Synapomorphies

Answer 20

• More mobile jaw

- Ctenoid scales - thin scales composed of bonelike material and characterized by a serrated margin

Question 21

Acanthopterygii - Atherinomorpha (Flying Fish, Grunion, Needlefish, Guppies, and Swordtails)

Answer 21

Protrusible jaw that is modified

Question 22

Acanthopterygii - Percomorpha (Perches, Sunfish, Cichlids, Flounders, etc.)

Answer 22

Pelvicfins with one spine and five soft rays; pelvic and pectoral girdles are joined

Question 23

Synapomorphies of Sarcopterygii

Answer 23

• Paired fins with long muscular lobes extending below the body and have a bony central axis
• Pulmonary vein
• Scales made of cosamine (dentine-like material as opposed to enamel-like material)

Question 24

Subclass Dipnoi

Answer 24

• Autostylic jaw suspension
• Teeth are scattered over the palate and fused into tooth ridges
• Diphyceral tail - tail is continuous with the dorsal and anal fins
• Thin scales embedded into the skin
• Internal lung structure
• Two-chambered atrium
• Pulmonary circulation (blood supply to the lungs)
• Bile salts (where it first evolved)
• Estivation - a period of dormancy that is usually induced by a lack of water. The fish burrow into the mud and metabolism is reduced

Question 25

Subclass Actinistia

Answer 25

• One living genus Latimeria (Coelocanth)
• First dorsal fin lacks lobe
• Lacks a maxilla
• Curious rostral organ
• Ossified swim bladders that is filled with fat