Thursday Jan 27 th
‐ A distressed group: in the middle of their 3 major extinction due to what we
due to them (fishing, etc.)
‐ Targeted for beauty products: shark oil is supposed to make you look younger,
shark skin is good for “leather” products
‐ Targeted for health products: blood and cartilage of sharks said to regenerate
cartilage in our bodies. Pills of shark cartilage – said to cure cancer.
‐ **** Worst threat: shark fin soup (illegal): said to have aphrodisiac properties –
NOT true, but people believe it because of how big and aggressive sharks are.
This is the cause of decline in shark populations.
‐ Sharks have low fecundity – makes them more at risk. (Cannot produce very
many babies and don’t give birth every year. Very slow growth rate: don’t start
breeding until it’s old. Makes it very susceptible for over‐hunting.
‐ Shallow waters used for “nurseries”. Shallow waters remove predation risk
from other sharks. Very susceptible to habitat destruction.
‐ Legislation and people are trying to save Chon.’s but they are more and more
endangered. Especially fresh water sharks.
Osteichthyes (last big group we will look at) “True Fishes” ‐ Bony fish
‐ We are all fish! (But we’re terrestrial)
‐ The synapomorphy for Ost. is not bone – but the gas bladder. Bladder crystals
covered in guanine (base pair nucleotide) crystals (shimmery quality in blush
makeup: found in bat guano!!)
‐ Bone is a hard tissue. It has a huge percentage of the crystal hydroxyapatite
(calcium), which makes it hard. More dense because there’s less water then
‐ Osteoblasts (holes) are trapped within the matrix of collagen fibers and other
proteins and then ner