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 AgnathaLampreys 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

• 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/reeflife/sea2i1.html