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26 Cards in this Set
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Phylum Chordata
Subphyla |
Subphylum Urochordata(Sea Squirts)
- Subphylum Cephalochordata (Lancets) - Subphylum Craniata (hagfishes & vertebrates) - Infraphylum Hyperotreti(hagfishes) - Infraphylum Vertebrata (vertebrates) |
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Subphylum Craniata
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The hagfishes and all vertebrates are CRANIATE: possess a skull that surrounds the brain & some sensory organs
- skull may be either bone or cartilage (2 types of connective tissue) |
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Infraphylum Hyperotreti:
Hagfishes |
- all marine, in benthic (bottom) region, ~60 species
- feed on inverts in sediment, may enter live/dead fish and eat from inside - most primitive craniates |
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Hagfishes:
Anatomy |
Skull consists of cartilaginous bars
Retain notochord through adult stage Body is elongate (eel-like) Lack jaws; mouth with 4 pairs of tentacles Lack paired fins - Either lack eyes or have vestigial eyes - Possess slime glands, are excessively slimy - Circ system partly open, partly closed - Have a main branchial heart & several accessory hearts |
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Infraphylum Vertebrata:
Vertebrates |
- characterized by VERTEBRAE, hollow rigid structures that form tube surrounding & protecting dorsal nerve cord
- vertebrae may be of bone or cartilage |
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Class Petromyzontida:
Lampreys |
- marine & freshwater
- larvae filterfeeders, adults lgly parasitize other fish - |
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Class Ptromyzontida:
Lamprey Anatomy |
- Lack jaws; have sucking mouth with teeth and rasping tongue
- Eel-like body form - No scales or paired fins - Gill slits (7) on side of head (water enters and exits through slits) - Skeleton made of cartilage - Can tolerate very high iron levels in blood and tissues - Only juveniles retain notochord |
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Lamprey Reproduction
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- Many lampreys live as adults in the ocean but in rivers as juveniles
- Typically return to river to mate - Juveniles are called ammocoete larvae |
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Class Chondrichthyes: Sharks, Skates, Rays & Allies
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- primarily marine, few freshwater
- carnivore or scavengers - |
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Chondrichthyes: External Anatomy
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- Cartilaginous skeleton
- Have moveable jaws with teeth - Ventrally located mouth - Paired appendages (fins) - Heterocercal (asymmetrical) tail - Gill slits (5-7) on side of head - Water enters through mouth or spiracles (specialized openings through which water enters) - Have a CLOACA, or common external opening to urinary & reproductive tract |
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Chondrichthyes: Scales
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tractChondrichthyes: Scales
- Sandpaper-like skin, covered with placoid scales (flattened rectangular base plate which is embedded in the skin) - These are lost in adult ratfishes & chimaera - Teeth are modified placoid scales, in rows |
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Chondrichthyes:
Internal Anatomy |
- Breathe via gills; all but skates (which use spiracles) aerate gills via the mouth
- Possess a liver to remove wastes from blood - Blood cells produced in spleen and Leydig’sorgan - Spiral valve in lower intestine; increases surface area for absorption - Lack swim bladder or lung, sink if not swimming - Large brain size for body size in many species |
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Subclass Elasmobranchii: Sharks, Skates and Rays
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Sharks are:
- Elongate; fast swimmers - Somewhat laterally compressed - Mostly predatory w sharp teeth - Among largest living fish - Skates & rays are: - Dorso-ventrally flattened - Mostly benthic, some shallowly burrow - Some filter feed while swimming - Some have stingers or electric charge |
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Subclass Holocephali: Chimaeraor ratfishes or ghost sharks
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- Gills are covered with OPERCULUM (like bony fishes)
- Plate-like crushing teeth for feeding on molluscs - Many have venomous spine anterior to dorsal fin |
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Bony fishes:
General Characteristics |
- Both marine & freshwater species; some capable of limited time out of water (lungfishes)
- Carnivores, herbivores, detritus feeders, some filter feeders |
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Bony Fish:
External Anatomy |
- Skeleton made of bone (except in paddlefish and sturgeons)
- Jaws with limited mobility, many with teeth - Terminal or ventral mouth - Paired fins - Homocercal(symmetrical) tail - Single gill opening on each side, covered by bony operculum (pumps water) |
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Class Sarcopterygii: Lobe-finned Fishes
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- Small group; 8 living species
- Fins are lobed and connected to body by single bone; lack rays - Can “walk” across substrate on these fins - Lungfishes have air-filled sacs used as lungs in gas exchange (can withstand drought) - Direct ancestor of land vertebrates - Very likely that these should not be included in the same Class as the remaining fish |
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Class Actinopterygii:
Ray-finned Fishes |
- No muscular lobes associated with fins
- Instead, fins are thin layers or skin with thin bony rays - Swim bladders (gas-filled sacs) function to regulate buoyancy - Includes vast majority of living fishes |
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Fishes:
Feeding and Digestion |
- Most modern fishes are predators, usually swallowing prey whole
- Some are filter-feeders - Some are herbivorous (e.g., carp, wood-eating catfish) - Complete digestive system like other vertebrates - Stomach stores food - Small intestine primary site of digestion and absorption |
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Fishes:
Circulation and Gas Exchange |
- CLOSED circulatory system
-Two-chambered heart pumps blood through arteries, capillaries, and veins - Red blood cells contain HEMOGLOBIN - Most fish exchange gases primarily w gills (a few have lungs) - Counter-current exchange (water & blood flow in opp directions)m inc efficiency |
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Fishes:
Nervous System I |
- Central nervous system w brain & spinal cord
- Receptors for temperature, touch, smell, vision, hearing, & balance - Ear often connects to swim bladder to aid in sound detection - Eyes lidless & lens moves back & forth to focus (unlike other vertebrates) - Lateral-line system –sensory pits along side detect motion, perhaps low frequency sounds - Most fish display electroreception (detect electrical fields generated by other organisms) - Some (e.g., sharks) find prey this way -Some fish (e.g., electric eel) produce strong current for defense & to shock |
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Fishes: Osmoregulation
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- Freshwater fish naturally absorb water, lose electrolytes (salts & other ions) thru diffusion
- Marine fish naturally absorb electrolytes, lose H2O thru diffusion - Fish kidneys & gills are the primary osmoregulatory organs |
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Freshwater Fishes:
Osmoregulation |
- Actively absorb ions across gills
- Reabsorb little water in kidneys - Much dilute urine - Do not drink water |
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Saltwater Fishes:
Osmoregulation |
- Eliminate ions by excretion, defecation, and active transport across gills
- Reabsorb much water in kidneys - Small amounts of strong urine - Drink water |
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Fishes:
Osmoregulation and Excretion |
Diadromousfishes migrate between freshwater and saltwater and must have both mechanisms
- Some marine fish (e.g., sharks) store N-ous wastes (urea) in tissues to reduce the concentration gradient - Most N-ous waste in form of NH3 & is excreted across gill surfaces - Remainder excreted through cloaca as urea, creatine, or creatinine |
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Fishes:
Reproduction |
- Sexual reproduction, external(most) or internal fertilization
- Most oviparous, some ovoviviparous, and a few viviparous - Most have limited or no parental care of embryos (lay many eggs) - Some brood embryos (e.g., seahorses) or even provide post-hatching care of young (e.g., catfishes) |