powerpoint 4 Flashcards
class chondrichthyes
class of cartilagenous fish
- prismatically calcified (triangles)
- loss of bone; cartilage as a synapomorphy
cartilage
- avascular
- made of chondrocytes
- releases AIF
AIF
angiogenesis inhibitory factor
- stops blood vessels from forming in cartilagenous areas
- nutrients and waste travel by diffusion
why were people killing billions of sharks
to make anti cancer pills
how does bone form
bones need blood vessels to deliver oxygen
- different from cartilage on a tissue level
claspers
- synapomorphy of sharks
- misnomer
- act as a siphon bw cloaca and the other shark
what species first evolved independent fertilization
sharks, 200 mil yrs before mammals
siphon sac
some sharks have a seawater filled bag used to push semen through
3 types of birth
oviparous
ovoviviparous
viviparous
oviparous
carrying eggs in an egg case
- hard/leathery shell
- twins are RARE, except for the west coast skate
west coast skate
produces 4, 5, or 6 embryos in one hard case
ovoviviparous
egg hatches in utero and birth is “live”
- even after using up egg sac they stick around for 3-4 months
- some eat unfert eggs
- some eat siblings
tropohemata
egg sacs penetrate gills/heads of some embryos and feed them that way
viviparous
live birth
- placental attachment like mammals
- analagous structure in sharks (pseudo/yolk sac placenta)
- umbilical scar
-
k-selected strategy
- slow growth
- late maturity
- few babies
- maternal care*** not sharks
ex: dolphin
r-selected strategy
- fast growth
- earlier maturity
- many many babies
- no maternal care
ex: oak tree
the four cartilagenous fish synapomorphies
cartilagenous skeleton
claspers
chronic tooth replacement
placoid scales
