Chondrichthyes (Sharks) Flashcards
what does chondrithyes mean?
cartilage fish
what are some characteristics about condrichthyes
- cartilaginous skeleton
- paced scales
- teeth replacement
- no gas bladder
- spiracle
- variation on jaw suspension
what is special about sharks?
they are secondary cartilaginous
- they ancestors were bony and now they are not cartilage is mineralized
what kind of scales do shark have?
placoid scales
- made with enamel and dentine
how do sharks teeth replacement work?
they come from within the mouth like a conveyer belt
what are the 4 types of jaw suspension sharks use?
- autodistylic
- amphistylic
- holostylic
- hyostylic
explain autodiastylic jaw
there’s 2 connection points between the upper jaw and chondrocraium
- lower job is connected to the upper jaw
explain amiphistylic jaw
upper jaw is attached by 1 ligament and suspended by hyomadibula
explain holostylic jaw
upper jaw is fused to chonrocraimium
explain hyostylic jaw
1 connection point but strong support from hyomandibula
- jaw can pop out
explain the sensory system of sharks
vision
- good at low light
chemoreception
- high sensitivity to smell
electroreception
- ampullae of lorenzini on the tip of their face allows them to sense electricity from muscles and water
lateral line
- cluster of cells that can detect movement of other fish
what are the lineages of sharks?
- holocephacii
- selachi
- batoida
- early elasmobranchs
explain the characteristics of holocephacii sharks
(type of jaw, feeding, reprodcution)
aka ratfish or chimera
- holostylic jaw
- oviparous
- bottom feeder
- no spiracle
explain the characteristics of the early elasmobranchs (type of jaw, feeding, reprodcution)
fast swimming apex
- amphistylic jaw
- spikes
explain the characteristics of selachi
hammer heads
- hyostylic
- oviparous
- subterminal head
how do sharks remain buoyant
cartilgous is lighter than bone
fatty liver (oil floats)
how do sharks hunt?
- smell
- vision
- lateral line
- eletroreception
what is something different about shark reproduction
they have something called
“psedoviviparity” where the embryo lives in the uterus in sac for some time then does not
what are batoidea and explain characteristics
rays and skates
- large fins
- hyostyic jaw but modified for suction
- modified teeth for crushing
- oviparous: mermaid purses (eggs)
