1. Osteichthyes

2. Osteichthyes Means fish with bony skeletons
There are over 20,000 species of bony fish

3. Where Do Most Fish Live?
Most fish live in the epipelagic zone

4. Types of Fins Tail Fin (CAUDAL FIN)
Paired Fins (PECTORAL and PELVIC FINS)
Medial Fins (DORSAL and ANAL FINS)

5. Rayed Fins
Ray-finned fish have fins supported by a fan-shaped array of bones
Makes the fin light, collapsible, and easy to move
Ray-finned fishes are the most diverse group of living vertebrates, making up nearly half of all vertebrate species.

6. External Anatomy of a Fish

7. External Anatomy

8. Caudal Fins Caudal fins have different shapes
1.  Homocercal --> Top and bottom halves the same size
a.      Rounded (Low A.R.)
b.      Truncate (Intermediate A.R.)
c.      Forked (Intermediate A.R.)
d.      Lunate (High A.R.)
2. Heterocercal --> Top half different size than bottom half

9. Types of Caudal Fins

10. Types of Caudal Fins
Heterocercal – often found on sharks

11. Nervous System Most fish have a complex sense of smell
Used to detect prey, mates and predators
Smell is detected in the nares (nostrils)
Fish also have taste buds
Found in the mouth, fins and skin
Catfish have taste buds on barbels (whiskers)
Rely on vision
Eyes focus by moving closer or further from the object they wish to view
Covered by a nictitating membrane – clear membrane that allows the fish to see while protecting the eye

12. Fish Senses
Sight – some fish can see color and can see in very dim light
Hearing – fish can hear
Smell – fish have nostrils used for smelling
Touch – fish can feel objects against their skin
Lateral line- A system of canals on the sides of fishes that helps fish detect changes in pressure, vibrations and currents

13. Lateral Line
Fish “hear” via their lateral lines, a line of pressure sensors running along each side of the fish that pick up pressure waves (= sound) in water. When someone pounds on an aquarium, that creates waves of pressure in the water that, to the fish, would be analogous to cupping your hands and pounding on your ears--NEVER POUND ON A FISH TANK!

14. Functions of the Lateral Line
Detect changes in pressure and vibrations and currents
Detect prey
Swim together in a school
Detect predators on the side or behind them
Pick up vibrations from the swimming together of other animals

15. Lateral Line

16. Movement Most fish swim with an S motion
A rhythmic side to side moving from the head to the tail
Controlled by bands of muscle called myomeres
Run parallel along the sides of the fish
Visible in fish you eat
Makes up 75% of the fishes weight
White muscle is used for bursts of speed
Red muscle is used for constant locomotion
The fins are used like rudders to change direction in the water
Some fish move by moving only their fins and not their body

17. Myomeres

18. BUOYANCY

19. Maintaining Buoyancy To maintain buoyancy the fish will either:
Adjust the density of its body by using a SWIM BLADDER
They will adjust the density of the components of their insides (they will consume lighter weight ions and leave the heavier ones in the surrounding water)

20. SWIM BLADDERS A swim bladder is a balloon-like structure that is:
inflated to make the fish rise higher in the water
or deflated to make the fish sink lower

22. No Swim Bladder
Some fish like Tuna do not have a swim bladder and must swim fast to prevent sinking
Some fish like catfish do not have a swim bladder and spend their life on the bottom

23. Respiration
Fish use gills to absorb oxygen from the surrounding water

24. Parts of a Gill
Gill Arch - stiff structure that supports the gill filaments and the gill rakers
Gill Rakers – prevent food from clogging up the gill filaments
Gill Filaments – fingerlike projections where oxygen is absorbed and carbon dioxide is removed

25. Parts of a Gill

26. Excretion and Osmoregulation
Marine fishes
Drink constantly
Less blood is filtered
Water is reabsorbed
Freshwater fishes
never drink
Lots of nephrons
Ions are reabsorbed

27. Fish Reproduction
Most fish have internal sex organs that we cannot see.
fish gonads (sex organs) produce gametes (sex cells) only at certain times.
These times must be the same for both males and females and must be timed to the most favorable conditions.

28. Fish Reproduction Fish may only reproduce when there:
1. Is enough of the right kind of food
2.There are enough hours of light each day
3. The water is the right temperature

29. Fish Reproduction Includes:
Courtship: a series of behaviors designed to attract mates
Spawning: a release of gametes into the water
Copulation: a direct transfer of sperm into a females body

30. Fish Reproduction Most fish reproduce by spawning.
This is when the female swims and lays eggs on plants or sand in the water
The male fish swims behind her depositing sperm into the water where some of it may land on and fertilize the eggs

31. Fish Reproduction
Some fishes are hermaphrodites. They have both male and female gonads
Hermaphrodism is more common among the deep-water fishes. (Gourami)

32. Fish Reproduction Sex Reversal
Males may change to females or females to males (ex. Clownfish)

33. Sex Reversal
Among some species of anemone fishes a single large female who mates only with a single large dominant male inhabits each sea anemone. All others are small non-breeding males. If the female disappears her mate changes into a female and the largest of the non-breeding males becomes the new dominant male. The new female can start spawning as soon as 26 days after her sex change.

34. Feeding
Fish can be either carnivorous or herbivorous (mostly carnivorous)
The teeth will tell you what they eat
Used for grasping and holding the prey
Prey is usually swallowed whole
Usually have one preferred food source
A type of fish, anemone, urchin, etc.
Fish that feed on algae are called grazers

35. Behavior Territoriality
An established area that the fish protects against invaders
Some are only territorial during mating period others are for life
Thought this helps ensure there is enough food for the fish
Defended by aggressive behavior like making themselves appear larger or by chasing other fish
Fights are rare

36. Behavior
Schooling
4000 species of fish school at some point in their lives
Can provide protection against predators
Can cause confusion
Less likely to be the one eaten if there are thousands of other fish around you
Can increase swimming efficiency by reducing the drag of the water
Can be advantageous for mating or feeding

38. Class Osteichthyes Characterized by having: Bone in their skeleton
An operculum covering the gill openings
A swimbladder or lungs
True scales
Paired fins
Homocercal tail (Exception lungfish – diphycercal)
Mouth terminal
Two chambered heart
Sexes separate (Sex reversal in some)
Fertilization external for most
Excrete ammonia

39. Class Osteichthyes
The bony fishes are the most diverse class of fish. ~24,000 species
Osteichthyes are divided into two subclasses
The lobe-finned fish (Sarcopterygians)
The ray-finned fish (Actinopterygians).
*Most modern fish are members of the ray-finned, Teleost subdivision.

42. Sarcopterygians
Sarcopterygians are the fish most closely related to modern amphibians, reptiles, birds, and mammals = terrestrial vertebrates
This subclass includes the lungfish and coelacanth. Coelacanth were thought to have become extinct at about the same time as the dinosaurs, until a live specimen was found in 1938

43. Sarcopterygians Characteristics: Muscular lobe associated with fins
Have lungs for gas exchange
Live in areas with seasonal droughts
Can breathe air if water stagnates
Can withstand desiccation
Burrow in the mud
Have enamel on the teeth

44. Sarcopterygians
Can survive drought by remaining in aestivation for 6 months or more
Aestivation = dormant state
After rain fills the lake or riverbed Lungfish emerge from their burrows to feed & reproduce

47. Lungfish - Found in Australia & Madagascar

48. Australian Lungfish

49. African Lungfish

50. Lungfish scales
Cosmoid scales

51. Lungfish Circulation

52. Coelacanth
                                                            

53. Actinopterygians Ray-finned fish (Fins lack muscular lobes)
Have swimbladders to regulate buoyancy
~23,900 species

54. Chondrosteans (Fresh water fish)
Include sturgeons and paddlefish
Sturgeon eggs make caviar

55. Caviar = Sturgeon eggs

56. Paddlefish

57. Subdivisions of Teleostei
Superorder Ostariophysi
Order Cypriniformes (minnows, carps)
Order Siluriformes (catfish)
Superorder Protacanthopterygii
Order Esociformes (pikes)
Order Osmeriformes (smelts)
Order Salmoniformes (salmon, trout, whitefish)
Superorder Paracanthopterygii
Order Gadiformes (cod, hakes, pollock)
Superorder Acanthopterygii
Order Percoidei (perches, snook, basses)
Order Pleuronectiformes (flounders, soles)
Order Perciformes (mackerel, tuna, swordfish)

58. Actinopterygians The Teleosts
Teleosts are modern day ray-finned fish
Use their fins and body wall to push against water for locomotion
Some secrete mucus to reduce friction
Most teleosts are carnivores swallowing prey whole
Herring & paddlefish are filter feeders
Teleosts have pyloric ceca (outpockets in the small intestine to increase absorption)

59. Ganoid Fish Scales Found on non-teleost bony fishes
Usually diamond shaped bony scales
“Heavy armor”
Gars – Alligator Gar

64. Cycloid Fish scales
Found on teleost fishes
Light, thin, & flexible

65. Ctenoid Fish Scales Teleost fishes
Have comblike ridges along the exposed edge to reduce friction (drag)