Opener: Articles
•Up to 100 mil caught each year (1 for 1)
•Uses: meat, fins ($150/bowl sfs), lubricants, artificial skin, corneas,
anticlotting agents, oil, vitamin A, white cell products, Prep H!
condroitin for cartilage…
•Studies: anticancer (squalamine, immune system, no vessels in
cartilage…
•Apex predators
•Sharks have large ranges…
•Hammerheads attracted to mating areas by electromagnetic pull…
•Sharks are not good for “game fish” due to 3 reproductive
reasons…
•How do we manage species? Limits, quotas, no finning,
Repellent: ????
• Made from?
• Good against?
• Used for?
Yum-yum yellow!
Class Agnatha
Lampreys and Hagfish
• “Jawless” (no jaws but
cool mouth!) Class
Agnatha
• Hagfish Produce lots of
slime for protection
• Hagfish can tie in knots
to remove slime and get
a “grip” on food
Class chondrichthyes
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Cartilagenous fish
Chondros = cartilage
Ichthys = fish
Sharks, skates, rays
Been around 280 million yrs.
– 2 x longer than the dinosaurs
Class chondrichthyes
• Skeleton made of cartilage –
tough elastic tissue (nose,
ears)
• True bones absent
• Almost all marine
• Negatively buoyant – will
sink if stop swimming
• Charactertistics
– Jaws with teeth, paired fins,
active lives
Shark facts!
• Sharks responsible for only
6 human deaths per year
• For every human killed by
sharks, humans kill more
than 16 million sharks!!!
Shark skin
• Placoid scales/dermal
denticles – tiny teeth like
structures, feels like sandpaper
• As sharks grows, scales do not
increase in size, just grows
more
• Collagen in skin acts like a
spring to help with propulsion by
the tail
Shark teeth
• Most powerful jaws on
planet!
• Upper and lower jaws
move
• Sharks can grow and
lose over 20,00 teeth in
their lifetimes!
• Different species =
different shaped teeth,
depending on what they
eat!
Cookie cutter shark
Shark digestion
• Can store food for
months using
sphincter muscles
• U-shaped stomach,
strong acid /enzymes
to dissolve food
• Indigestible things
(bones, non-food)
vomited
• Liver up to 25% of
body weight, ours
2.2%
Stomach rugae
Diet and eating habits
• Fish, molluscs, marine mammals, other
sharks, plankton
• Prey on weak, ill
• Different species, different food
– Hammerheads – stingrays
– Bull sharks – other sharks
– Tiger shark – sea turtles
• Sharks can’t eat –
– Moses sole – fish secretes a chemical and
the sharks lets go
– Puffer fish – shark swallows the fish and it
blows up in throat, killing shark
Reproductive systems: female
Female: age at
maturity is 19 in
spiny dogfish;
gestation is 2
years!!!
Uterus: mature female (19)
Male: age
of maturity
is 11years!
Shark reproduction/anatomy
• Females larger
• Males have claspers – transfer sperm
• Birth can be
– 1) viviparous - eggs hatch in female and
young fed by placenta
– 2) oviparous – deposit eggs, hide among
corals
– 3) ovoviviparous – eggs hatch and babies
develop inside female, no placenta. Pups
eat unfertilized eggs and each other for
food
Reproduction: development in egg
cases (oviparous)
Cloaca: common opening
Rectal Gland???
Heart and Gills?
Brain!!
Shark sight
• Sight – good eye sight, can
see in dim light, sensitive to
light
• Nictitating membrane
• Structure similar to ours –
pupil can dilate
• Reflective membrane:
• tapetum lucidum to “reuse”
light (dawn/dusk)
Shark smell
• Excellent sense of smell
• Sharks can detect a concentration as
low as 1 ppb of some chemicals, amino
acid!!
• Can detect smells up to hundreds yards
away
• H2O continually flows thru their
nostrils – giving them olfactory info
• Nostrils only used for smell, not
breathing
Lateral Line: vibrations…
Ampoules of Lorenzini
Electroreception, salinity (?), pressure
Semicircular canals: balance
Fins
• Rigid
• 5 different fins
– Paired pectoral fins – provide lift, maneuvering
– Paired pelvic fins – stabilize
– One or two dorsal fins – stabilize the shark (may
have spines)
– Anal fin – provides stability
– Caudal fin – propels and provide lift
•
Muscles: swimming
Swimming
• Some sharks are fast-swimming (up to 40 mph or 64.4 kph),
some are slow-swimming bottom dwellers that eat shell fish,
and some are slow-swimming filter-feeders that sieve tiny
animals and plants to eat.
• Cannot stop suddenly or swim backwards
• Pectoral fins cannot bend upwards like a fish, limiting its
swimming ability to forward motion. If a shark needs to
move backwards, it uses gravity to fall, not swim backwards.
Sharks must swerve to the side in order not to hit
something - they cannot simply stop.
• Some sharks (like the great white shark) swim by propelling
itself through the water using its tail. The fins are only
used for balance. Other sharks, like the whale shark, move
their bodies from side to side to propel themselves through
the water.
• A shark must keep swimming or it will sink
Cool sharks
Past and present uses of shark
• Before sandpaper, skin was used to smooth
and polish wood
• Japanese warriors used shark skin on handles
of swords
• Teeth used as weapons, arrowheads and on
harpoons
• Skin used as leather
• Meat is eaten – as shark or passed off as
scallop or other fish
• Liver oil used a source of vitamin A
• Cartilage used in cancer treatment
• Fins used in soup
• Used in Chondroiton
Causes of death
• Humans, other sharks
•Every year, millions of sharks killed
by fisherman for their fins, fins cut
off and animal thrown back to drown
•Sharks overfished as food source
•Harvested for cartilage/products
• http://www.seasky.org/ree
flife/sea2i1.html