Ectotherms lecture 2 Flashcards Preview

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Flashcards in Ectotherms lecture 2 Deck (21):

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