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Fishes
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- 2. Fishes Of vertebrates themost: - Ancient group - Appeared 530 MY ago - Small, bottom-dwelling animals without jaws, teeth, or paired fins - Only vertebrates for 50 MY - Evolved fins and then bony armor - Most fish lost armor - Diverse group - 28,000 species 2
- 3. Fishes All aquatic andhighly adapted for aquatic life - Virtually all fresh and marine waters - None are terrestrial, although some can tolerate periods of dry air Variety of sizes - Smallest vertebrate (0.7 cm) - Whale shark (15 m) - Most will continue to grow throughout lifetime - Growth is temperature dependant (higher temp = larger size) - Annual rings in scales, otoliths (ear bone), and other boney parts 3
- 4. Fishes Skin has bothepidermis and dermis - Epidermis secretes slimy mucus (reduces friction) - Dermis produces scales - Scales of the same material as our teeth (form of emamel) Skeleton begins as cartilage and replaced by bone in most - Ribs and appendicular skeleton present - Pectoral and pelvic fins 4
- 5. Fishes Movement - Bundles ofsegmented muscle tissue (myomeres) - Have W-shaped arrangement - Mostly used for swimming - Very efficient form of locomotion (don’t have to fight gravity) - Myomeres produce s-shaped swimming motion - Fish push on water 5
- 6. Fishes Feeding and Digestion -Jawlessness restricted fish to deposit and filter feeding (some scavenging) - Jaws allow for a predatory lifestyle - Small, sharp teeth - Produced throughout lifetime - Flexible jaws engulf large prey - Prey swallowed whole 6
- 7. Fishes Respiration - Most havegills (more efficient than other aquatic animals) - Some have cutaneous respiration - Some can breathe air Circulation - 2 chambered heart with single circuit - Blood pumped through gills then to body 7
- 8. Fishes Nervous system - Smallbrain compared to other vertebrates - Cerebrum - high center (very small) - Cerebellum - coordination of movement (relatively large) - Brain stem - automatic activities (relatively large) - Sense organs - Evolved because light doesn’t travel far in water and sound and pressure waves travel very far - Lateral line system - Eyes - Chemoreceptors - Hearing 8
- 9. Fishes Excretion Kidneys for nitrogenous wastes(osmoregulation too) ● Primitive marine fishes are isotonic ● Most marine fishes are hypotonic ○ Loose water and gain salt ● Freshwater fishes are hypertonic ○ Gain water and loose salts 9
- 10. Fishes Reproduction and Development -Most dioecious - Most with external fertilization - Marine fish reproduce in large schools - Freshwater fish have elaborate mating - Some with a high degree of parental care 10
- 11. Fishes Groups of fish 1.Jawless fishes (Agnatha) ○ 111 species 2. Cartilaginous fishes (Chondrichthyes) ○ 970 species 3. Bony fishes (Osteichthyes) ○ 27,000 species ○ Separated into ray-finned (Actinopterygii) and lobe- finned (Sarcopterygii) 11
- 12. Superclass Agnatha Jawless fishes Commonfeatures - Lack: - Jaws - Internal bones - Scales - Paired fins - Porelike gill openings 12
- 13. Superclass Agnatha Class Myxini- hagfishes - Entirely marine - Feed on annelids, crustaceans, or decaying animals - Almost blind - Keen sense of smell - Attracted to dead whales and fish 13
- 14. Superclass Agnatha Class Myxini- hagfishes - Two toothed plates on tongue that grasp prey - May tie knot with body for leverage 14
- 15. Superclass Agnatha Class Myxini- hagfishes - Generate slime to ward off predators 15
- 16. Superclass Agnatha Class Myxini- hagfishes - Bodies are isotonic with seawater - Primary heart with three accessory hearts - Reproductive biology largely a mystery - Few, large eggs - No larval stage 16
- 17. Superclass Agnatha Class Petromyzontida- lampreys - 50% are parasitic - Others do not feed as adults - Anadromous - ascend freshwater rivers to breed - Adults marine 17
- 18. Superclass Agnatha Class Petromyzontida- lampreys - Reproduction - Males build nest in spring/summer - Females shed eggs and males sperm - Die shortly after - Eggs adhere to stones and pebbles - Larvae hatch 2 weeks later - Leave nest and burrow into substrate - Live as filter feeders for 3-7 years - Metamorphosize into adults 18
- 19. Superclass Agnatha Class Petromyzontida- lampreys - Feeding - Parasitic forms attach to host - Rasp wound with tongue - Inject anticoagulant to prevent clotting 19
- 20. Superclass Gnathostomata Jaws representa major advancement for vertebrates - Freed from bottom feeding - Longer list of feeding opportunities Evolved from gill arches - In primitive fish resemble gill arches - Still occurs in shark development 20
- 21. Superclass Gnathostomata Paired fins -Pelvic and pectoral - Stabilization during swimming - Began as skin folds? 21
- 22. Superclass Gnathostomata Class Chondrichthyes -970 species - All but a few are marine - Include the largest fish - Body fusiform (sharks) or flattened (skates and rays) - Generally with tough, leathery skin - Placoid scales - Skeleton is cartilaginous - Teeth are mineralized 22
- 23. Superclass Gnathostomata Class Chondrichthyes -Elasmobranchii - sharks, skates, and rays - Sharks - Heterocercal tail - vertebrae extend into the dorsal lobe of the caudal fin - Paired pectoral and pelvic fins - Dorsal fin - Paired nostrils - Claspers in males 23
- 24. Superclass Gnathostomata Class Chondrichthyes -Elasmobranchii - sharks, skates, and rays - Sharks - Well developed senses (needed to be an efficient predator) - Olfactory organs used to long- distance detection - Lateral line used at moderate distances - Vision and ampullae of Lorenzini used at close distances 24
- 25. Superclass Gnathostomata Class Chondrichthyes -Elasmobranchii - sharks, skates, and rays - Sharks - Reproduction may be oviparous, ovoviviparous, or viviparous 25 https://youtu.be/KW8PKZF53bQ
- 26. Superclass Gnathostomata Class Chondrichthyes -Elasmobranchii - sharks, skates, and rays - Skates and rays - Half of all elasmobranchs - Dorsoventrally flattened - Enlargement of the pectoral fins - Specialized for bottom dwelling - Some rays have venomous spines on tail 26
- 27. Superclass Gnathostomata Class Chondrichthyes -Holocephali - chimaeras or ratfish - Split from elasmobranchs 380 MYA - Jaws bear flat plates instead of teeth - Upper jaw completely fused to cranium - Gills covered by single operculum 27
- 28. Superclass Gnathostomata Class Chondrichthyes -Holocephali - chimaeras or ratfish - Split from elasmobranchs 380 MYA - Jaws bear flat plates instead of teeth - Upper jaw completely fused to cranium - Gills covered by single operculum 28
- 29. Superclass Gnathostomata Clade Osteichthyes- bony fishes - Class Actinopterygii - ray-finned fishes - Every fish you’ve eaten, caught, seen, owned,...etc. - Class Sarcopterygii - lobe-finned fishes - Much rarer 29
- 30. Superclass Gnathostomata Class Actinopterygii -31,000 species - Four clades recognized - Birchirs - have lungs and ganoid scales. Restricted to west Africa (ex: African lungfish) - Chondrosteans - 27 species of freshwater or anadromous fish (sturgeon, paddlefish) - Neopterygians - heavy scaled and boned fishes with well developed swim bladder (bowfin, gars) - Teleosts - modern bony fishes 30
- 31. Superclass Gnathostomata Class Actinopterygii -Teleosts evolved several morphological characters that allowed them to become so dominant and diverse - Heavy dermal armour (i.e., ganoid scales) was replaced by lighter scales (e.g., cycloid, ctenoid) - Faster swimmers (better at being a predator and avoiding predators) - Symmetrical tail replaced heterocercal tail - Faster swimming ability (all force directed backwards evenly) - Other fins were made more flexible and adapted for other uses - I.e., lure in angler fishes, venom-delivering spines in scorpionfishes 31
- 32. Superclass Gnathostomata Class Actinopterygii -Teleosts evolved several morphological characters that allowed them to become so dominant and diverse - Refinement of the swim bladder - Better buoyancy control - Changes to the jaw to allow for suction feeding, protrusion of the jaw, and pharyngeal jaws - Wider array of prey items 32
- 33. Superclass Gnathostomata Class Sarcopterygii -Possessed lungs and gills - Ancestrally had heterocercal tail, but diphycercal tail is derived condition - Powerful jaws, enameled scales, and fleshy paired lobed fins - Possibly used for locomotion - 8 species remain - 6 lungfishes; 2 coelacanths 33
- 34. Superclass Gnathostomata Class Sarcopterygii -Lungfishes vary in their ability to withstand terrestrial environments - Australian lungfishes rely on gills - South American and African lungfishes can live out of water for long periods - Can even survive drying of their body of water is able to burrow 34
- 35. Superclass Gnathostomata Class Sarcopterygii -Coelacanths - Once only known from fossils - Discovered living in 1938 - Two species - one near Madagascar, one near Philippines 35 https://youtu.be/rYOf2wIoxgo