Ectotherms lecture 2 Flashcards
(21 cards)
What are the craniates?
Chordates that have a cranium (skull), neural crest, pharyngeal gill clefts (gill slits or ears)
A higher metabolic rate, two chambered heart, hemaglobin and kidneys
What phyla do we first see development of a head in?
The myxini
What are the features of the agnathans?
Median fins, two chambered heart, simple digestive system, sens organs, external fertilization
What are the features of the myxini?
The most basal craniate with a cartilaginous skull, retention of the notochord, a small brain, eyes, ears and nose opening
Fond only in marine environments
What are the petromyzontida?
The lamprey, an example of an agnathan
What are the features of the lamprey?
Cartilaginous skeleton, rudimentary vertebrae, sucker like oral disc, 7 pairs of gill apertures, moderately well developed eyes, dioecious (separate sexes)
A long marine larval stage followed by adult stage in freshwater
What are the five classes in the gnathostomata?
Chondrichytes, osteichthyes, amphibian, reptilian, mammalia
What are the critical innovations in the super class of the gnathostomata?
Jaws and a mineralized skeleton
Scales and teeth
Paired fins
Lateral line
How is the mineralised skeleton believed to have developed?
It started as dental elements present within the head, these develop into teeth then denticles and then a skull and finally a skeleton
What are the classes in the chondriocytes?
Selachiformes, Rajifromes and Chimaeriformes
What are the features of selachiformes?
350 fusiform species Low metabolic rate Variable dentition Lamnid sharks: no nictitating membrane Carcharhind sharks: nictitating membrane
What are the features of rajiformes?
Stingray, eagle ray, manta ray rhinobatoids
Electric rays-capacitor effect
What are the features of chimaerifromes?
Operculum, upper jaw fused to skull
What are the characteristics of chondrichthyes?
Heterocaudal fin Ventral mouth Skin with placoid scales Cartilaginous endoskeleton Two-chambered heart 5-7 pairs gills and exposed gill slits No operculum No swim bladder or lung Internal fertilization and separate sexes
What are the features of the shark skeleton?
It advances on the agnatha with the presence of jaws and teeth, paired fins (pectoral and pelvic) and an enlarged braincase
What are the features of the osteichthyes?
Bony skeleton, numerous vertebrae, homocercal tail
Skin with embedded scales (though some are without scales)
Paired fins with rays of cartilage or bones
Terminal mouth, usually many teeth
Gills supported by bony arches and covered by operculum
Swim bladder often present
Two chambered heart
Separate sexes, usually external fertilization
What are the bony fish groups?
The class osteichthyes which is split into the subclasses of actinopterygii ( chondrostei, holostei, teleostei), crossopterygii (actinistia) and dipnoi
What are the features of the actinopterygii subclass?
Contains a bone skeleton rather than a cartel age one with many spines and ribs with a complex skull of several layers
What is the lateral line system?
It is a canal along the side of a fish containing pores that open into tubes supplied with sense organs and are sensitive to low vibrations
What animal is in the subclass crossopterygi?
The coelacanth
What animal is in the subclass dipnoi?
The African lungfish
