Upload
lionel-ferguson
View
221
Download
7
Tags:
Embed Size (px)
Citation preview
I. Fishes – Biology
E. Osmoregulation1. Chondrichthyes & Sarcopterygii
• Concentration of solutes in blood similar to seawater (isosmotic) or slightly higher (hyperosmotic)
• Retain urea and TMAO in blood (toxic to most other vertebrates)
• Absorb water through gills and skin• Salts excreted by glomerular kidneys and rectal gland• Large volumes of hypotonic urine
2. Actinopterygii/Osteichthyes• Concentration of solutes much lower than seawater
(hypo-osmotic)• ~14 ‰ vs. ~35 ‰
• Drink seawater• Salts excreted by kidneys (often aglomerular) and
chloride cells in gills• Small volumes of isotonic or hypertonic urine
I. Fishes – Biology
F. Buoyancy Regulation1. Chondrichthyes
• Large liver – squalene (~20% less dense than seawater)• Up to 20-25% of body weight
• Continuous swimming• Lift from broad, flat head
2. Sarcopterygii• Lipid-filled swim bladder
3. Actinopterygii/Osteichthyes• Gas-filled swim bladder
• Physostomes: Fill SB by gulping air• Physoclists: Fill SB using gas gland (Root effect)
• Some fishes lack a swim bladder• Active pelagic species (tunas, mackerel)• Demersal or benthic species (scorpionfishes)
I. Fishes – Biology
G. Sensory Systems1. Smell/Taste
• Most fishes have a highly developed sense of smell• Detect food, mates, predators, navigational
information• Sensory cells in olfactory sacs on both sides of head
• Sacs connected to outside through nares (nostrils)• Sharks especially sensitive to scent of blood (1 ppm)
• Hammerhead sharks: nostrils on ends of “hammer”; swing head side to side; orient by comparing concentrations on left/right
• Salmon locate home stream by scent (imprinting)• Taste with taste buds in mouth and on lips, fins, skin,
barbels
I. Fishes - Biology
G. Sensory Systems2. Lateral line
• Clusters of sensory cells (neuromasts) in small canals lining head and along sides of body• Sensitive to vibrations in water
• Used for orientation, detection of prey and currents, avoidance of predators and obstacles
3. Inner ears• Calcareous otoliths rest on sensory hairs (maculae)
• Detect sound waves + changes in fish attitude• Help to maintain equilibrium and balance• Can be used to determine age of fish
I. Fishes – Biology
G. Sensory Systems2. Lateral line
• Clusters of sensory cells (neuromasts) in small canals lining head and along sides of body• Sensitive to vibrations in water
• Used for orientation, detection of prey and currents, avoidance of predators and obstacles
3. Inner ears• Calcareous otoliths rest on sensory hairs (maculae)
• Detect sound waves + changes in fish attitude• Help to maintain equilibrium and balance• Can be used to determine age of fish
I. Fishes – Biology
G. Sensory Systems4. Electroreception
• Found in Chondrichthyes• Ampullae of Lorenzini• Detection of prey, navigation• Extremely sensitive (may be less than 1 nV/cm)
• Can detect a marine mammal’s electric field 3 m away
• Used in combination with other senses
Kalmijn (1971)
A) Flatfish (Pleuronectes platessa) buried in sand
B) Flatfish in box of agar made with seawater (blocks mechanical vibrations); flow-through
Spotted dogfish shark (Scyliorhinus canicula)
C) Chopped fish in box of agar made with seawater; flow-through
D) Flatfish in electrically insulated box of agar made with seawater
E) Electrodes buried in sand
F) Electrode buried in sand; chopped fish on surface
I. Fishes – Biology
H. Feeding1. Chondrichthyes
a. Bite pieces from large prey• Tiger shark – Diverse stomach contents• Great white shark – Wound and wait• Cookie cutter shark – Cut out chunks
b. Ingest smaller prey whole• Nurse shark – Benthic invertebrates
c. Filter plankton – Gill rakers• Whale shark – Warm• Basking shark – Cold• Megamouth shark• Manta ray
I. Fishes – Biology
H. Feeding2. Actinopterygii/Osteichthyes
a. Capture large prey whole• Large mouth, small teeth• Ex: Barracudas, frogfishes
b. Crushers – Crush prey• Teeth usually fused into bony plates• Ex: Pufferfishes, porcupinefish, boxfishes
c. Pickers – Ingest smaller prey whole• Small mouth, tiny teeth• Ex: Butterflyfishes
d. Grazers• Small mouth, strong teeth• Ex: Parrotfishes, surgeonfishes
e. Filter plankton • Gill rakers• Ex: Anchovies, sardines, herrings
I. Fishes – Biology
I. Reproduction1. Modes
a. Oviparityb. Ovoviviparityc. Viviparity
2. Strategiesa. Pelagic
• Often in aggregations• Many small eggs, high mortality• Ex: Tunas, sardines, parrotfishes
b. Benthic• In pairs or aggregations• Eggs usually attached or sinking• Ex: Smelt, salmon
c. Brood hiders• Benthic spawners; no parental care• Ex: Grunion
d. Guarders• Care of eggs until hatching, often beyond• May involve territoriality• Ex: Damselfishes, blennies, gobies
e. Bearers• Eggs carried by parent until hatching• Care usually by males• Ex: Seahorses, pipefishes, jawfish
Fig. 10-33
I. Fishes – Biology
I. Reproduction3. Hermaphroditism
a. Synchronous• Ex: Hamlets
b. Protogyny• Ex: Wrasses
c. Protandry• Ex: Anemonefishes
4. Larval developmenta. Planktotrophic
b. Lecithotrophic
Fig. 10-35
Fig. 10-34
I. Fishes – Biology
J. Schooling• One form of shoaling behavior• Displayed by ~25% of all fish species• Some fishes school throughout life, others only when juveniles,
feeding• School sizes vary
• Atlantic herring – 4580 m3
• Pacific herring – 15 miles long!• Positioning in school may involve
• Vision• Other senses (mechanical vibrations, olfaction, hearing)
1. Typesa. Mobile schools
• Usually consist of single species, size rangeb. Stationary schools
• May contain multiple species, sizes2. Functions
a. Protection against predatorsb. Increased swimming efficiency?c. Beneficial when feedingd. Beneficial when mating
I. Fishes – Biology
K. Migration• Generally related to feeding and/or reproduction• Diel
• Horizontal• Ex: Grunts (day on reef, night feeding in seagrass
beds)• Vertical
• Ex: Mesopelagic fishes
• Large Scale• Ex: Skipjack tuna feed in Eastern Pacific, spawn in
Western and Central Pacific
I. Fishes – Biology
K. Migration1. Anadromous
• Spawn in fresh water• Spend most of life in ocean• Ex: Salmon (seven species) in Pacific Ocean
• Spawn in shallow areas of rivers/streams• Semelparous (adults die after spawning)• Young migrate downstream to ocean after 0-5
years• Spend 3-7 years in ocean before returning to
home stream• Homing behavior enabled by olfactory imprinting• Important source of nutrition for wildlife, forests
I. Fishes – Biology
K. Migration2. Catadromous
• Spawn in ocean• Spend most of life in fresh water• Ex: Eels (16 species) in Atlantic Ocean
• Spawn in Sargasso Sea (400-700 m or deeper)• Semelparous• Eggs hatch into leptocephalus larvae• Larvae spend a year or more as plankton then
undergo metamorphosis into juveniles• Adults spend 10-15 years in fresh water before
migrating to Sargasso Sea to spawn