1. Chapter 10: Fishes

2. Fishes Vertebrates: presence of a backbone
1st fishes lacked paired fins and jaws
Evolved 425 million years ago

3. Jawless Fishes No jaws or paired appendages
Skeletons composed of cartilage
Bodies lack scales

4. Hagfish Lack vertebrae Called “slime eels” Bottom-dwelling
Act as scavengers or feed on live prey
Eat carcass from inside out
Slime glands provide physical protection
Normally separate sexes

5. Lampreys
Freshwater and saltwater
Larvae are filter feeders

6. Cartilaginous Fishes (Chondrichthyes)
Skeletons made of cartilage
Jaws and paired fins
Skin is covered by placoid scales
Teeth are modified placoid scales

7. Sharks Streamlined bodies (excellent swimmers)
Swim with sideways tail sweeps (caudal fin)
Slightly denser than water
Will sink if they stop swimming
Large livers
Produces squalene (oily secretion)

8. Sensory systems
Eyes
Eyes lack eyelids
Clear nictitating membrane to protect eye
Can perceive color
Well-developed olfactory receptors
Helps find prey

9. Lateral line system
Canals along length of animal’s body and over the head
Neuromasts can detect vibrations in fluid that fills the canals
Used to locate predators and prey

10. Teeth continually lost and replaced Food swallowed whole
Osmoregulation
Retain large amounts of nitrogenous wastes
Can enter freshwater by reducing levels of nitrogenous wastes in body fluids
Digestion
Teeth continually lost and replaced
Food swallowed whole

11. Sperm produced in paired testes
Reproduction
Sperm produced in paired testes
Transferred to female through groove in claspers
Paired ovaries and oviducts
Carries eggs to oviducts
Internal fertilization

12. Eggs hatch within mother’s uterus
Oviparity
Eggs laid outside the body
Embryos develop in protective case
Attach to hard surfaces on seafloor
Ovoviviparity
Eggs hatch within mother’s uterus
No placental connection is formed

13. Viviparity
Young directly attach to mother’s uterine wall
Mother’s uterus produces milk that is absorbed by

14. Skates and Rays Flattened bodies
Enlarged pectoral fins that attach to the head
Reduced dorsal and caudal fins
Eyes on top of head
Spiracles: openings for passage of water
Gill slits on ventral side
Lack anal fin
Pavement-like teeth used for crushing prey
500 species

15. Rays Swim by moving fins up and down Tails are streamlined
Contain venomous barbs or spines
Some species grow large
Ovoviviparous

16. Skates Swim by creating a wave, resulting in a glide
Tails have small fins
Lack venomous spines
Fleshier
Oviparous
Release eggs in leathery rectangular egg case called a mermaid’s purse

17. Electric organs in head that can deliver 220 volts (ex: electric rays)
Defense mechanisms:
Electric organs in head that can deliver 220 volts (ex: electric rays)
Can be used to navigate and stun prey
Stingrays have hollow barbs connected to poison glands
Can inject venom

18. Chimaeras Ex: ratfish, rabbitfish, and spookfish Large pointed heads
Long, slender tails
Gills covered with an operculum
Water taken in through nostrils
Oviparous
Flat plates used to crush prey
Bottom dwellers
35 species

19. Bony Fishes (Osteichthyes)
25,000 species
Has swim bladder (lungs)
Bones
Bony scales
Fin rays
95% of all species of fishes

20. Coelacanths Lobed, paired fins 150-250m deep; rocky areas
Skeletons made of bone; vertebral column made of cartilage
Ovoviviparous
Keep high concentration of urea in blood to remain isotonic to seawater

21. Ray-Finned Fishes Dominant vertebrates in ocean
Fins attached to body by fin rays
Fish scales:
Ganoid, Cycloid, and Ctenoid
Body shape determined by characteristics of its habitat

22. Coloration:
Vision used as primary sense in finding food and communicating
Pigments
Colored compounds found in chromatophores
Can alter color by moving pigments
Structured colors
Produced by light reflecting from crystals located in specialized chromatophores (iridophores)
Colorless
Immobile

23. Countershading
Back colored dark colors
Shades graduate on the sides to belly which is white
Can camouflage fish
Disruptive coloration
Background color usually interrupted by vertical lines
Makes it difficult for predators to see fish

24. Used to blend with their environment
Poster colors
Bright, showy color patterns
May advertise territorial ownership, aid foraging individuals to keep in contact
Can be warning coloration
Cryptic coloration
Used to blend with their environment

25. Locomotion:
Drifting with the current
Burrowing
Crawling on the bottom
Gliding
Swimming

26. Respiration and Osmoregulation:
Use gills to extract oxygen from water, get rid of carbon dioxide, and aid in maintaining proper salt balance

27. Nervous system:
Olfactory receptors in olfactory pits
Taste receptors located on surface of head, jaws, tongue, mouth, and barbels
Vision
Eyes lack eyelids
Sides on head

28. Feeding
Carnivores
Herbivores
Filter-feeders
Adaptations to avoid predation:
Can swallow large amounts of air or water to inflate their bodies
Can leap out of water
Some secrete a mucous cocoon at night

29. Reproduction
Most are oviparous
Gonads are paired and suspended from roof of body cavity by membranes called mesenteries
Development of eggs and sperm is seasonal

30. Pelagic spawners
Release a lot of eggs into water
Males fertilize eggs
Fertilized eggs drift with the current
No parental care
Advantages: offspring widely dispersed
Disadvantages: high mortality

31. Benthic spawners
Live closer to shore
Produce eggs that are larger with more yolk
Nonbuoyant eggs
Spread over vegetation
Large numbers produced
No parental care

32. Brood hiders Guarders Bearers Hides its eggs No parental care
Care for offspring until they hatch
Can defend territory if needed
Bearers
Females lay eggs in male’s mouth or abdomen
Incubates in mouth or abdomen until they hatch

33. Hermaphrodites
Both testes and ovaries
In 14 families of fish
Synchronous
Has functional gonads of both sexes at one time
Sequential
Changes from one sex to another
Can change from females to males (protogyny) or males to females (protandry)

34. Fish Migrations Common May occur daily or seasonally
Seasonal association with spawning, changing temperatures, or feeding
Daily associations with feeding and avoiding predators

35. Salt  freshwater to spawn
Can move between freshwater and saltwater
Fresh saltwater to spawn
Called catadromous
Ex: freshwater eels
Salt  freshwater to spawn
Called anadromous
Ex: salmon