Animal biodiversity 5 - fish Flashcards
what is the super class agnatha?
without jaws
3 features of the Ancient Agnatha- Ostracoderms
1) shell skinned heavily armoured
2) bony plates and scales surfaced in enamel and dentine (like teeth)
3) lacked pectoral fins (poor swimmers)
what are the 2 classes of modern agnatha?
1) hag fish
2) lampreys
3 features of the body structure of hag fish and lampreys
1) lack paired fins and jaws
2) no armour
3) skeleton cartilaginous
how do hagfish feed?
scavengers, enter the body through an opening and eat from the inside out
what water do lampreys live in?
adults may be freshwater or marine but they spawn in freshwater and larvae live in the sediment of streams
describe the skeletal structure of lampreys
skeleton is made of cartilage containing no collagen in a vertebral column
what is the Superclass Gnathostoma 2 features?
1) jaws
2) 2 pairs of appendages
state one hypothesis for the evolution of jaws
evolved from 2 pairs of skeletal rods located between gill slits near the mouth, anterior rods either lost or incorporated in cranium
describe the class Placodermii
extinct plate skinned heavily armoured jaw fish
what are 4 features of the Class Chondrichthyes?
1) flexible endoskeleton made of cartilage
2) tooth like structures called placoid scales
3) developed jaws and paired fins
4) 5 pairs of gill pouches
what species does class chondrichthyes include?
sharks, rays, dogfish
what are chondrichthyes reproductive strategy?
oviparous, ovoviviparous, or viviparous
what is the job of the heterocercal tail and wing-like pectoral fins on chondrichthyes?
provide lift because body is negatively buoyant
what are the 4 sense adaptations of Chondrichthyes?
1) sharp vision, not colour
2) cup shaped smell receptors
3) lateral line system to detect pressure changes
4) electroreceptive organs in the head detect electric fields
what is the definition of Osteichthyes?
bony fishes with calcium phosphate endoskeleton
what is the significant of the gas sac in Osteichthyes?
used for buoyancy and as oxygen reservoir in periods of drought or stagnation
how do Osteichthyes keep water flowing across the gills?
gill pouch covered by an operculum, with pharyngeal muscles acting like bellows
what are the 3 classes of osteichthyes?
1) ray finned
2) lobe finned
3) lung fish
features of the Class Actinistia (lobe-finned fish)
heavy pectoral and pelvic fins which may have walked in tetrapod motion
features of the Class Dipnoi (lung fish)
have lungs and nostrils, live in stagnant ponds
3 features of the Class Actinopterygii (ray-finned fish)
1) reduced scales for increased mobility
2) better adapted fins and tail for manoeuvrability
3) maxilla is now free and articulated, giving more efficient jaw
