Fish Flashcards
What are the key features of the phylum Chordata?
Notochord, dorsal tubular nerve chord, postanal tail, pharyngeal slits, endostyle/thyroid gland.
What are the three subphylums of the phylum chordata?
Vertebrata, Cephalochordata, and Urochordata.
What are two hypotheses of the evolutionary origins of fish? Which is the most likely?
Originated from tunicates (sac-like sessile filter feeders), and originated from lancelets (amphioxus, free-living). Lancelet evolution is more likely.
What are the two superclasses of the subphylum Vertebrata?
Agnatha and Gnathostomata.
What are the three key subclasses in the superclass Agnatha?
Myxini (hagfish), petromyzontida (lampreys), and ostracoderms (group - extinct).
What is the class in Agnatha?
Cyclostomata.
What are the two key extinct groups in the superclass Gnathostomata?
Placoderms and Acanthodians.
What are the two classes in the superclass Gnathostomata?
Chondrichthyes and Osteichthyes.
What are the subclasses of Chondrichthyes - Gnathostomata?
Elasmobranchii (sharks and rays) and Holocephali (whole heads).
What are the subclasses of Osteichthyes - Gnathostomata?
Actinopterygii (ray finned fish - most fish) and Sacropterygii (lobe-finned fish).
What are the defining features of the Superclass Agnatha class Cyclostomata?
Circular mouths, teeth made of keratin, no/paired fins, poor swimmers.
What are the key features of the extinct group Ostracoderms?
Mineralized bony heavy armor.
What are the key features of the superclass Gnathostomata?
Jaws, paired fins.
What are the key features of the extinct group Placoderms?
First jawed fish, plate skin - heavy armor around head, mostly bottom dwellers, primitive autostylic jaw with true paired fins. Heterocercal tail.
What are the key features of the extinct group Acanthodians?
“Spiny sharks,” small column feeders, teeth with large head and eyes, streamlined round bodies, more lightweight armor. Heterocercal tail. Hyoid (visceral arch) - attachment between chondrocranium and the skull. Amphistyllic jaw.
What are the key features of the Chondrichthyes subclass Elasmobranchii (sharks and rays)?
Spiracles, sub-terminal mouth with protrusible jaw - detached from skull, heterocercal tail, fins supported by ceratorichia, placoid scales, clasper, cloaca - joint anal and urogenital, ampullae of lorenzini.
What are the key features of the Gnathostomata class Chondrichthyes?
Cartilaginous skeleton, placoid scales, separate sexes with internal fertilisation (claspers in males), 5-7 gill pairs - slits in sharks and rays, covered by operculum in chimaeras, replacement teeth, oil liver for buoyancy.
What are placoid scales?
Scales that feel rough in one direction and smooth in the other.
What’s a clasper?
Sexual organ modified from pelvic fin in males - used for sperm.
What are the key features of the subclass Holocephali?
Chimaeras/ratfish, non-protrusible jaw - top attached to the skull, operculum, diphycercal (equal) tail, naked skin with few placoid scales, no cloaca - separate anal and urogenital opening. Grinding plates instead of teeth.
What are the key features of the class Osteichthyes?
Bony fish, 96% of all living fish, true bony skeleton - endochondrial bone, scales - ganoid, cycloid, or ctenoid. Bony operculum covering gills, bony fin support (lepidotrichia), lung or swim bladders.
What’s the operculum in Osteichthyes?
A bony plate covering gills - can use pressure to draw water over the gills for improved respiratory efficiency.
What are swim bladders (lungs)?
Gas filled pouch branching from esophagus, efficient for neutral buoyancy and modified for air breathing in some groups.
What are the key features of the Osteichthyes subclass Sarcopterygii?
Lobed fins, only eight species, heavy scales, pulmonary and systemic circulatory systems incompletely separated.
What are the infraclasses of Sacropterygii?
Actinistia - lobe finned and 2 species, Dipnoi - two breathing - air and water.
What are the infraclasses of Actinopterygii?
Chondrostei - cartilage bones, ganoid scales. Neopterygii - new fins - primitive.
What are the key features of the division Teleostei in the infraclass Neopterygii?
“perfect bones,” most diversity, bony lightweight skeleton, homocercal tail supported by uroneural bones, cycloid or ctenoid scales, moveable maxilla and premaxilla, swim bladder. - fast
What does having a moveable maxilla and premaxilla in Teleostei do?
Allows for suction feeding.
What are the main two types of swimming in fish?
Undulatory (primitive swimming - muscular contraction - swim via waves), and Oscillatory (wing or oar-like swimming - using an anchor as a pivot).
What are the two types of drag in water - adaptations to counter?
Friction drag “stickiness,” and pressure drag (pressure difference between head and tail). Streamlining + tucking in fins + mucous can reduce drag as well as breaking up pressure drag with spines and scales.
How do fish stay afloat and move up and down in the water? What are the two different kinds?
Buoyancy - dynamic (moving) or static (non-moving).
What are some examples of dynamic buoyancy?
Constantly moving - with pectoral fins and heterocercal tail to create lift - high energy cost.
What are some examples of static buoyancy?
Swim bladder, use of oils, fats, and buoyant ions.
What are the two different kinds of swim bladders?
Physostomous: gas-filled sac connected to the oesophagus. Filled with air by gulping and blood diffusion - emptied by mouth. Phytoclistous: sealed off from oesophagus, filled by blood diffusion and emptied at the end of the body.
What are the three main muscle types for power and control in swimming?
Flexors/extensors, protractors/retractors, and adductors/abductors.
What is the role of the caudal fin?
Propulsion and steering.
What’s the role of the dorsal and anal fins?
Prevent roll and helps propulsion in undulatory swimming.
What is the role of pelvic fins?
Control pitch and act as hydrofoils.
What is the role of pectoral fins?
Propulsion, turning, and stopping.
What are the key characteristics of fish vision?
Fisheye - doomed lens, unequal photoreceptors (cones for shallow water and colour, and rods for low light).
What are the key features of fish hearing?
Otoliths (ear bones) are dense, suspended in fluid move and send messages via cilia. Good for low frequency, high energy sound.
How can the swim bladder act for sound?
Amplifies sound due to being air filled - sonic muscles allow vibration. Good for high frequency/low energy sound.
What are the key features of fish smell?
Nares = nose. Goes in one side, out the other. Can smell pheremones, mates, homing, and chemical alarm systems.
What are the key features of taste in fish?
Taste receptors in mouth, lips, skin, and fins.
What is distant touch in fish?
Fish can detect touch from far away due to their lateral line (canal with neuromasts (hair cells with cupola - free or protected in canal organs)). Used for object avoidance, schooling, and prey location.
What is electroreception in fish?
Can be done with specialized neuromasts with no cilia. Ampullary organs - weak, low frequency - passive electrolocation (elasmobranchii), and Tuberous organs sensitive to higher, stronger frequency - active electrolocation.
