Gills are delicate filamentous structures that are heavily vascularized (may be visible or hidden by gill covers)
occur in primarily the cephalic region
maximize seurface area for respiration
sharks: gills are on interbranchial septa (septal gills) and tips of interbranchial septa acts as valves that can close external gill slits
bony fish: gills covered by an operculum.
large common opercal cavity for all gills
inter branchial septa reduced so that primary gill lamellae extend freely into opercular caity (these are aseptal)
Gas Exchange and Water Balance: Circulation
heart: resposible for pumping blood through the system
under autonomic control
adjusts to match metabolic needs
Fish: blood only passes through heart 1 time so only need 1 atrium and ventricle (also have sinus venosus, and bulbus arteriosus but are non contractible)
considered either 2 or 4 chambered
blood in capillary beds loses pressure. not a problem for fish as blood doesnt need to overcome large gravitational forces and they dont have large metabolic needs
Gas Exchange and Water Balance: Excrition
Fresh water Teleosts (perch): hyper osmotic (water in solutes out) excrete highly gilute urine and limit water intake
Opisthonephric Kidney: eliminates excess water
ammonia secreted through gills as special glands in gills absorb salt
Marine teleosts: hypo osmotic (water out solutes in) drink water and excrete concentrated urine
Sharks: convert ammonia to urea and retain it in their blood making them iso osmotic (high tolerance to urea). excrete excess salts via special rectal gland
Sensory Abilities: Nervous system
3 components: central, peripheral, autonomic nervous systems
parts of brain that are used more are larger and mor complex
Bottom feeding fish: rely on smell to find food thus have large olfactory lobes and telencephalon
Surface feeding fish: rely on sight to find food thus have large optic lobes and small olfactory apparatus
Sensory Abilities: Sensory reception
4 sensor modalities: chemo, mechano, photo, and thermoreceptors
Chemoreception: most primitive and in all animals
salmon: can go from open sea to hatch site based off of dilute chemical trail
Bony fish: have lateral lines (sense organ dectecting movement in fluid) seen running down the sid
Sharks: some have modified lateral organ with electro receptors that can sense magnetic feilds
Viviparous: (sharks, dogfish) embryos develope in female. needs a uterus
Oviparous: (perch, most fish) embryo developes inside an egg. eggs laid and strewn across weeds
Oviviparity: eggs retained in mother during development
these a a reflection of environmental stresses affecting offspring survival
External Fertilization: fertilization in external environment. pheremones used to attract mates. eggs laid in strategic locations (temperature predation water quality)
Internal Fertilization: fertilization in female reproductive tract. these individuals developed elaborate neural and pheremonal mechanisms for facilitating copulations.
propose an adaptive advantage of the heavily ossified skull
perch are carniverous fish. how might hinged jaws aid in prey capture?
Based on the size and shape of the teeth do you think the fish chews its prey or swallows it whole?
how is the shape of the perch well adapted to minimize drag during swimming?
which fins are involved with steering and which are involved with in propulsion? which fins would be used to slow the fish after a quick burst of speed? do any of the fins appear to have no obvious function?
is your specimine male or female?
what kind of scales do perch have?
how are the gills of perch well suited to facilitate gas exchange?
propose a function for the gill rakers
how is the shark well adapted to minimize drag during swimming?
which fins are involved with steering and which are involved in propolsion?
what is the most likely function of the spiral valve in the intestine?
is your specimen male or female?
why are opercula considered and evolutionary advancement in the bony fish?
the caudal fins of perch and dogfish sharks differ in shape. what effect might theis have on their swimming?
what advantage do fish with swim bladders have?
what features do you think might favor internal vs external fertilizations?
how do the reproductive systems of the dog fish and perch differ? how does this relate to their mode of reproduction?
which regions of the brain are relativley more and less developed? what does this say about abilities of perch and shark?(seeing smelling maneuvering orienting and reasoning)?