FISH FACTS
PHYLUM CHORDATA • Dorsal Notochord-long rod that supports the body-becomes the vertebrae in most. • Dorsal Nerve cord-becomes the central nervous system. • Pharyngeal gill slits-openings in the throat for feeding & breathing-becomes the Pharynx in humans. • Tail-forms in embryos and extends past the anus.
Traits Shared by ALL Chordates
CLASSES OF CHORDATES The group we care about most in Marine Biology
CLASS PISCES SUBCLASS SUBCLASS
SUBCLASS AGNATHA • Jawless fish, that are the only vertebrate parasites. • Hagfish live in salt water • Lampreys live in fresh water • Have a sucker-like oral disk, with teeth that rasp the flesh & suck out juices from tissue.
CARTILAGINOUS FISH • 850 Species of Sharks, Rays, & Skates • Skeleton is made of cartilage. • External Gill slits. • Store oils & constant motion to stay afloat. • Scales are small bony plates (at one time used as sandpaper).
RAYS & SKATES • Flattened body for a bottom-dwelling niche • Spiracles & eyes on the dorsal side. • Mouth, nostrils & gill slits on ventral side. • Stingrays have a hollow barb. • Manta ray grows to 18’.
SHARKS • Close to 300 species. • Largest fish in the world-Whale Shark. • Can smell blood • Lateral line detect vibrations in the water • Ampullae of Lorenzini Sense changes in electrical field. We aren’t here to hunt humans, we are misunderstood!!!
Shark Food Facts • Many rows of teeth • Usually tear off pieces of food and swallow it whole • Strange things sharks have had in their digestive system: • Legs of lamb, horseflesh, part of a ham, front half of a bulldog, rear half of a pig, coal, 34 leather jackets, parts of a reindeer, telephone books, pots and pans, bottle of madeira wine, a keg of nails, kerosene lantern
CLASS OSTEICHTHYES(BONY FISH) • 96% of all fish belong to this group. • Bony skeletons, gill operculums. • Rigid bodies, flexible fins. • Swim bladders for buoyancy. • Chromatophores for color.
SKIN & SCALES • The skin of bony fish has chromatophores • Light, flexible scales for protection. • Produce mucus to reduce friction in water & protect against predators.
FINS & LOCOMOTION • Due to the rigid nature of their body, bony fish “flex” their fins for propulsion. • Paired fins are for fine movements. • Dorsal & Ventral are used to stabilize. • Caudal is for speed.
SWIM BLADDER & GILLS • Swim/air bladder-gas filled sac that can be used for buoyancy, sound & protection. • Gills extract Oxygen efficiently from water. • Blood flow in the filaments is opposite the flow of water resulting in the greatest amount of gas exchange!
LATERAL LINE • Lateral line is a series of pits on the side of a fish that lead directly to spinal cord. • It can sense the slightest movements in the water. (vibrations) • Schooling: fish use this sense to school..(about 80% of all species school at some point in their life) • Schooling helps with mating +Protection.
REPRODUCTION • Oviparous-both sexes spawn & eggs are fertilized externally. • Ovoviviparous-some incubate the eggs, internal fert., no nourishment, some species actually bear their young living! • Viviparous-internal, nourishment, all species bear their young living.
Migrations • Catadromous- Breed in the oceans but live in freshwater • Eels migrate to the Sargasso Sea, they spawn at depths of 300 meters and die when done
Anadromous- Breed in freshwater but live in salt • Atlantic Salmon makes multiple trips in its lifetime • Pacific Salmon only once
