i. Chondrichthyes
a.
Cartilaginous fish
b.
Sharks, skates, rays
c. 400 million years
d.
Sharks
i. Anatomy
1. Heterocercal caudal fins
2.
Teeth
a.
Multiple rows that
constantly replace
3.
No swim bladder
a.
Keep swimming
b.
Rigid pectoral fins
c. Squalene oil
4.
No operculum
a.
5.
Exposed gills
Scales = denticles
6.
Claspers
a.
Male reproductive
structure
ii. Hunt for food
1. Sound
a.
Sound travels 5x faster
in water
b.
Low-pitched =
splashing
2.
Smell
a.
3.
Vision/sight
a.
4.
Blood
Dilate their eyes
Ampullae of lorenzini
a.
Detect weak electrical
signals
5.
Taste
a.
Exploratory bites,
confirms whether they
should eat it
iii. Attacking humans
1. Mistake them for prey
a.
Surfer – looks like a
seal
b.
Spearfisherman –
stealing sharks food
2.
Occur in
a.
Shallow water
b.
Summer
iv. Reproduction
1. Internal fertilization –
claspers
2.
3 types of birth
a.
Oviparous – egg laying
b.
Ovoviviparous –
internal egg, live birth
(sand tiger)
c. Viviparous – live births
(placenta/umbilical cord)
lemon shark
e.
Skates vs rays
i. Skates are smaller/ rays are
larger
ii. Skates no stinger/rays have a
stinger
iii. Skates have a fin on their
tail/rays have a smooth tail
iv. Similarities
1. Enlarged pectoral fins
2.
Ventral gills