Fish Physiology Fish external physiology Mouth types: Caudal tails • Lunate, crecent • Forked • Truncated, rounded • Heterocercal • Eel-like Teeth: • NO teeth or tiny “sandpaper” teeth = swallow whole, teeth just keep it in • Flat blunt =crushing something’s shell • Sharp but broad teeth = chipping things off • Carnivore teeth = duh • Feathery teeth = filtering tiny plankton/algae/etc FISH SCALES – 3 main types PLACOID GANOID Magnified ! CTENOID FISH SCALES – 3 main types • Ganoid – armor • Ctenoid –more flexible, less tough – the most common type of scale • Placoid – sharks have this, it is actually like tiny teeth poking out of the skin • • • • • • • • Touch Similar to our senses Taste Sight Smell Hear Sense movement of water (lateral line) “electrical” (not all fish) Magnetic fields (some fish,. And whales) Special Fish senses Fish hearing Smelling and sight • Nostril = water flows through, it isn’t connected to anything. Fish eye lens • Fish eyes are small. • Mammal eye Fish eye Lateral Line Organ • Senses movement Electrical sensing EVERY MUSCLE PRODUCES A LITTLE ELECTRICITY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Some fish can sense that! Electrical sensing Electricity production EVERY MUSCLE PRODUCES A LITTLE ELECTRICITY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 200 Volts 500 Volts http://www.youtube.com/watch?v=y9wktSQdyaE&feature=related TASTE • • • • You have taste buds, so do Fish They work the same way, But some fish’s taste buds are ALL OVER HIS FACE!!! A catfish has 10 X as many taste buds on his face than in his mouth. Gills = get dissolved oxygen Gills Gill rakers Gill rakers Human lungs • At best, you can only take out 50% of the oxygen in the air. Gills can take out nearly 90 % of oxygen of water that flow over it. Getting the fuel eat Stomach (food normally taken whole) LIver pancreas Pyloric caeca blood Fats, proteins, carbs, All get broken down, Goal = glucose Gall bladder Intestines poop Fish digestive system Transporting the fuel and oxygen to the muscles – fish have two chambers, we have four Fish heart and circulatory system Do fish drink? • Fresh water fish never need to drink water, it soaks in all their cells all the time. • Salt water fish have to replace water all the time, so they drink A LOT! (and have a specialized way to pump the salt back out) Swim bladder.. Where does the air come from? Three basic reproductive/development strategies: • Egg layers – embryo nurtured by Oviparous a yolk, waste builds up in egg till hatching Ovoviparous • Mixture of both – typically eggs Viviparous • Live birth – embryo nurtured by held inside, till hatched mother in uterus via placenta, which also takes away waste from baby Oviparous – egg layers still have various spawning behaviors • Broadcast • Just sprayed out there • Substrate • Put on something specifically • Nest • A nest is made and the other is • Brooders • Eggs held in pouch or mouth invited in Ovovivparity – eggs held in, not laid until they actually hatch IN the mom first • Guppies • Mosquito fish • Many sharks ovoviviparous sand tiger shark • Mom has two uteri • 100s of eggs are held inside, • • • about 50 per uterus Baby has a yolk like any other. After hatching, they just stay in the mom for a while, they are very small. (NO PLACENTA) …. Only one, about 1ft shark comes out of each uterus a few months later…fat and happy!!!!... Why? Sand tiger shark • Marine bio trip picture. Viviporous – momma provides nourishment and takes away waste via a placenta… not just a yolk • This is common in mammals, (us, whales, etc.) but extremely rare in fish • Great white sharks have a mammalianlike placenta to nourish the babies till strong Reproduction summary Oviparity, viviparity, ovoviparity Egg: yolk or placenta, plopped out as egg or live Oviparity • Place where egg laid: broadcast, substrate, etc. Ovoviparity: • Held in till hatched, guppies • even “uterus canabalism” in some sharks Viviparity: • Extremely rare in fish, only in sharks most likely Fish Sex (gender) Fish are NOT genetically determined to be male or female. They, like reptiles, are male or female based on external forces Gender in fish 1) “normal” - Some fish grow up to be male or female and just stay that way regardless – temperature of the egg often determines male vs female 2) “Sequential hermaphrodite” – fish all start out as one gender and then switch with size or age 3) “Simultaneous hermaphrodite” – Fish perform as male or female at the same Gender in fish 1) “normal” - Most sharks and many fish are “normal” Gender in fish “Sequential hermaphrodite” – fish all start out as one gender and then switch with size or age Clown fish all start out male – turn female only later if big enough and paired correctly. Put two males together and the older/bigger will be come female Gender in fish “Sequential hermaphrodite” – fish all start out as one gender and then switch with size or age Blue head wrasses Most start as females, and there are a few “dominant” males that run the harem. Take out the dominant blue head male – largest female will turn into a male and run the harem. Gender in fish “Simultaneous hermaphrodite” – Fish perform as male or female at the same time. Hamlets – another reef fish is both male and female at the same time… he/she can mate with any fish that happens to come by (They do not seem to mate with themselves) Thursday we dissect Some things to keep in mind 1) Participation is required 2) Safe behavior is important. 3) Fish are preserved – smell is going to be strong – just get over it.