Vertebrates Flashcards
vertebrae
small skeletal elements that form a backbone
characteristics of vertebrates
- dorsal vertebral/spinal column
- anterior cranium(skull), with a large brain
- well developed circulatory system with a ventral heart
examples of the agnathans
lamprey and hagfish
agnathans
jawless fish
hagfish
-skeleton of cranium and cartilage only (no bone)
-no jaws, teeth made of protein (keratin), used to escape tissue from dead organisms
-can secrete tons of slime
(hag gag) to remember slime
lamprays
- also have cartilaginous skeleton/skull
- mostly parasites of fish
- no jaws but attach to host with sucker like mouth, scrape hot tissue with teeth of keratin
gnathostome
synapomorphy for vertebrates that have jaws and mineralized skeleton
how did jaws evolve?
- from gill arhches that supported pharynx around slits
- evolution of mineralized teeth made jaws more effective
- with evolution of jaws, gill slits no longer used for suspension feeding
common ancestor of gnathostome also evolved what?
fins
-allowing for efficient movement through water
chondrichthyans
- sharks and rays
- cartilagenous fishes
sharks
mostly predators (bulk feeding great white sharks) but some large sharks suspension feed (whale sharks)
rays
body is dorsoventrally flattened
some live on sea floor (sting rays, predators on invert)
-others inhibit the open ocean (manta rays)
-suspension feeders bring water and prey into mouth with large fleshy extensions
actinopterygii and sarcopterygii
- actin: ray fins
- sarco: lobe fins
- ancestor evolved outgrowths of gut (sacs) that could be filled with air
- sacs evolved into swim bladders in most ray finned fishes
- lungs in lobe fin lineage including tetrapods
actinoptergyii
- ray finned fishes
- fins are supported by delicate bones
- skeleton mineralized with calcium phosphate
- surface of refined fishes are often covered with scales
- gills covered by a hardened flap of tissue (operculum)
sarcopterygii
- lobe fins
- novel bones surrounded by muscle arose in these fins
- allowed common ancestor of lobe fins to support itself in shallow water
coelocanths
- thought to have gone extinct
- living organisms found in deep waters off africa
lung fish
- live only in swamps/ponds in the tropics of the southern hemisphere
- have functional lungs for breathing air!
- also have gills but in most the gills are not functional
tetrapods
- tetra:4 pod: foot
- skeletal changes in pectoral fins gave rise to tetrapod forelimbs (arms)
amphibians
- most have 2 life stages:
- aquatic larvae
- lack limbs
- respire via gills
- swim with muscular post anal tail
- adults may be aquatic, amphibious, or mostly terrestrial
- usually have limbs
- respire via lungs and across skin
- may or may not have a tail
- confined to moist habitats because:
- eggs have no shell, vulnerable to desiccation
- most have larvae that are aquatic
there clades of amphibians
- caudata
- anurans
- caecilians
caudata
- 500 species
- salamanders
- elongate, tailed body with 4 legs
anurans
- 5400 species
- frogs and toads
- anura means no tail
- elongated hind legs, webbed feet for hopping or swimming
caecilians
- 170 species
- legless, burrowing amphibians
- wormlike, burrow in soil in the tropics
- larvae not fully aquatic, develop in soil near water
sister clades of animals
reptiles and mammals