1. Biology of Fishes
Lesson 19

2. Terminology: Plural for fish is fish Fishes – multiple species of fish
“There are many fish in my tank”
Fishes – multiple species of fish
“The various fishes in the ecosystem demonstrate the diversity of animals”

3. Variety Fishes have a variety of shapes, sizes, colors Phylum Chordata
Subphylum Vertebrata
Have an internal skeleton including backbone and skull

4. Variety 3 major Classes 1) Jawless fishes 2) Bony fishes
3) Cartilaginous fishes

6. 1) Jawless Fishes Hagfishes and lampreys:
Although these ancestors did not survive to the present day, it is important to recognize that they
were enormously successful in their time, dominating
the scene for some 140 million years, from approximately to 350 MYBP.

7. 1) Jawless fishes
Have remain virtually unchanged for more than million years
Have survived through at least four major extinction events.
Most primitive fish species on Earth
Do not have scales, paired fins, or jaws

8. 1) Jawless Fishes Elongated bodies Sucker-shaped mouths
Feed by sucking on their prey
Typically parasitic
Feed on dead or dying fish
Skeleton made of cartilage

9. Characteristics
Believed to form a monophyletic group called the cyclostomes ("circle mouths")
Members of this group of fishes produce an excessive amount of mucus as a defensive measure

10. Characteristics
While they are virtually blind, they have four pairs of tentacles around their mouths that are used to detect food.
Tongue-like structure that has barbs on it to tear apart dead organisms and to capture their prey
Tongue secretes an enzyme that prevents blood from clotting in victim

13. What is the goal of the study?
Why is the discovery so important to evolutionary biologists?
What other implications do lamprey genetics bring light to in relation to human ailments?

14. Hagfishes Hagfishes are represented today by seven genera
76 species all contained within a single family, the Myxinidae
Have tentacles
They are restricted to marine habitats throughout the temperate and tropical zones of the world
Ex: Gulfs of Mexico and Panama.

15. Lampreys Lampreys are represented by ten genera
46 species all contained within a single family, the Petromyzontidae.
No tentacles

16. Habitat Native to Northern Atlantic Ocean Coevolved with fish species
First found in Lake Ontario in
Invaded through shipping canals

17. Habitat
Niagara Falls served as a barrier to the rest of the lakes, but canals have allowed lampreys to invade the other lakes
No coevolution exists here
Fish cannot survive lamprey’s attacks here
Great Lakes Fishery Commission releases chemicals to selectively kill lamprey larva and barriers to prevent adult species from moving upstream to spawn

19. 2) Bony Fishes Skeletons are made of bone
Incredibly numerous and diverse group
Approx. 50% of all vertebrate species are bony fishes
Majority are marine
Economically important as major protein source for global communities

20. 2) Bony Fishes
Take in water through their mouth and pass it over gills to breathe
Some need to keep moving to allow water to pass over gills
Oxygen then transferred to fish’s bloodstream
Then brought to the body’s cells

21. 2) Bony Fishes Oxygen-poor water is released through operculum
Operculum: flap of flesh covering the gills
Have one gill opening on each side of the head covered with operculum

22. peduncle

23. Bony Fish External Anatomy
Caudal fin: provides propulsion in water
Move to side-to-side
Where marine mammals move tails up and down

24. Bony Fish External Anatomy
Dorsal side – back side of fish
Dorsal fins: help stabilize fish and keep body from rolling over

25. Bony Fish External Anatomy
Ventral side – belly side of fish
Pelvic and Anal fins: provide stability

26. Bony Fish External Anatomy
Either side of fish
Pectoral fins: provide lift and propulsion
Assist in steering and moving vertically in water and column
Fins have fleshy, translucent membranes covering bony spines

27. Fin Modifications - Some fish do not have all fins described
Ex: Eel species – dorsal, pelvic, anal, and caudal fins are joined together
Ex: Mudskippers – modified pectoral fins allow animal to crawl on land

28. Bony Fishes Adaptations
Swim bladder – balloon structure filled with air near stomach and intestine
Prevents fish from sinking if it stops swimming

29. Swim bladder

30. Bony Fish Adaptations
Lateral line organ – detects vibrations in the water
Numerous small cavities that run along middle of fish

32. Bony Fish Adaptation Scales are covered in slimy mucus
Scales have a rounded shape

33. Checkpoint
Describe the function of each of the following types of fins in fish.
1) Caudal - _____________________________________
2) Pelvic - ______________________________________
3) Anal - _______________________________________
4) Dorsal - ______________________________________
5) Pectoral - ______________________________________

34. 3) Cartilaginous fishes
This group includes sharks, skates, and rays
Have been on Earth for almost million years ago
Evidence suggests many characteristics have not changed in over 100 MY

35. 3) Cartilaginous Fishes
Skeletons are made of bone-like substance called cartilage
Same as what makes up your nose and ears
They have no true bones or swim bladder
Lack of bones allows for flexibility
Cartilage not easily fossilized because it decomposes quickly

36. 3) Cartilaginous Fishes
Most common evidence are fossilized teeth
Teeth are made of very hard substances
Enameloid
Dentine

37. Cartilaginous Fish Adaptations
Placoid Scales - spiny tooth-like scales that are sharp to the touch
Embedded in animal’s skin (won’t flake off like bony fishes)
Make the skin feel like sandpaper when rubbed from tail to head
Rays skin feels like velvet from head to tail

39. Cartilaginous Fish Adaptations
Have 5 or more gill slits on the sides or bottoms of their bodies

40. Cartilaginous Fish Adaptation
Spiracles: structures on their heads to take in water
Water passes over gills and out through gill slits
Most species (except bottom dwellers) breath through their mouths
Must swim continuously to maintain flow of water over gills

41. Cartilaginous Fish Adaptation
Must swim continuously to maintain flow of water over gills
Nostrils are not for breathing, but for sense of smell
Sharks have an acute smelling ability

42. Types of Cartilaginous fish
Skates have flattened bodies and long tails

43. Types of Cartilaginous fish
Rays have similar body shapes, but poisonous stingers

45. Types of Cartilaginous Fishes
Sharks are best-known cartilaginous fishes
Over 300 shark species living on Earth today
Many have fusiform streamlined body shape
Rapid declines due to human activities, pollution, climate change, overfishing
Several countries have enacted protection for sharks

46. General Diagram of Shark Anatomy

47. Shark Adaptations Sharks have anywhere from 6-20 rows of teeth
Back rows serve as replacement teeth for when active teeth are damaged or lost
Believed that shark can go through 20,000 teeth in its lifetime

48. Shark Adaptations
Shark teeth are clues to the niches of specific species
Predatory sharks have razor sharp teeth to tear prey into small pieces
Bottom-dwelling sharks have large flat teeth to crush shells of invertebrates

49. Shark Adaptations Eyesight comparable to humans
Can detect blood nearly 0.3 miles away
2/3 of shark’s brain is devoted to detecting and processing smells
Also can detect slightest sound vibrations in the water
Uses lateral line system

50. Shark Adaptations
Have a sixth sense
Ampullae of Lorenzini - Sensing organ consists of tiny pores located near shark’s snout
Able to pick up smallest electrical impulses produced by other organisms
Impulses created by other’s muscle or heart contractions

54. Electrial Fields produced by animals in the water

55. Sharks: Great Ocean Predators
National Marine Sanctuaries – Channel Island: Swell Shark Video
What adaptations do these shark exhibit?
What physical characteristics do all the sharks in the video have in common?

56. Checkpoint
Give 3 ways in which cartilaginous fish are different from bony fish. 1) ___________________________________ ) ___________________________________ ) ___________________________________