1. Fish external physiology
Fish Physiology
Fish external physiology

2. Mouth types:

3. Caudal tails Lunate, crecent Forked Truncated, rounded Heterocercal
Eel-like

4. 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

5. FISH SCALES – 3 main types
PLACOID
Magnified !
GANOID
CTENOID

6. 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

7. Fish senses Touch Taste Sight Similar to our senses Smell Hear
Sense movement of water (lateral line)
“electrical” (not all fish)
Magnetic fields (some fish,. And whales)
Similar to our senses
Special

8. Fish hearing

9. Smelling and sight
Nostril = water flows through, it isn’t connected to anything.

10. Fish eye lens
Fish eyes are small.
Mammal eye Fish eye

11. Lateral Line Organ
Senses
movement

14. Electrical sensing
EVERY MUSCLE PRODUCES A LITTLE ELECTRICITY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Some fish can sense that!

15. Electrical sensing

16. Electricity production
EVERY MUSCLE PRODUCES A LITTLE ELECTRICITY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
200 Volts
500 Volts

18. 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.

19. Gills = get dissolved oxygen

20. Gills

21. Gill rakers

22. Gill rakers

23. Human lungs
At best, you can only take out 50% of the oxygen in the air.

24. Gills can take out nearly 90 % of oxygen of water that flow over it.

25. Getting the fuel eat Stomach (food LIver normally taken whole)
pancreas
Pyloric caeca
Gall bladder
Intestines
blood
Fats, proteins, carbs,
All get broken down,
Goal = glucose
poop

26. Fish digestive system

27. Transporting the fuel and oxygen to the muscles – fish have two chambers, we have four

28. Fish heart and circulatory system

30. 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)

31. Swim bladder.. Where does the air come from?

32. Three basic reproductive/development strategies:
Egg layers – embryo nurtured by a yolk, waste builds up in egg till hatching
Mixture of both – typically eggs held inside, till hatched
Live birth – embryo nurtured by mother in uterus via placenta, which also takes away waste from baby
Oviparous
Ovoviparous
Viviparous

33. Oviparous – egg layers still have various spawning behaviors
Broadcast
Substrate
Nest
Brooders
Just sprayed out there
Put on something specifically
A nest is made and the other is invited in
Eggs held in pouch or mouth

34. Ovovivparity – eggs held in, not laid until they actually hatch IN the mom first
Guppies
Mosquito fish
Many sharks

35. The famous ovoviviparous sand tiger shark
Mom has two uteri
100s of eggs 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?

36. Sand tiger shark
Marine bio trip picture.

37. 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 mammalian-like placenta to nourish the babies till strong

38. 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

39. Fish Sex (gender)
Fish are NOT genetically determined to be male or female. They, like reptiles, are male or female based on external forces

40. Gender in fish
“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
“Sequential hermaphrodite” – fish all start out as one gender and then switch with size or age
“Simultaneous hermaphrodite” – Fish perform as male or female at the same time.

41. Gender in fish
“normal” - Most sharks and many fish are “normal”

42. 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

43. 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.

44. 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)

45. Thursday we dissect Some things to keep in mind
Participation is required
Safe behavior is important.
Fish are preserved – smell is going to be strong – just get over it.