Fishies! And other things too….

Vertebrates The 4 basic characteristics of

chordates…. › Have a single, dorsal, hollow nerve chord› Gill or pharyngeal slits› a notochord › a post anal tail

Agnatha ("no jaws") is a superclass of jawless fish in the phylum Chordata, subphylum Vertebrata.

gnathostomes- all vertebrates with jaws

Jawless fish Has no paired fins or scales

Lampreys (30 species)Temperate regions, primarily freshwaterbreed in rivers/lakesattach to other fish and suck their blood, or

feed on bottom invertebrates

More Jawless Fish

Hagfish/slime eels (20 Species) Feed on dead and dying things Bore into pray and eat them from

the inside out Live in burrows, in muddy bottoms Skin is used to make leather

http://video.nationalgeographic.com/video/news/animals-news/new-zealand-hagfish-slime-vin/

Cartilaginous fishies

Cartilaginous fishes Includes: Sharks, rays and skates and

ratfishes Skeleton made of cartilage Moveable jaws Have paired lateral fins Placoid scales

Sharks!! Sharks

› fast swimming + predatory feeding› living fossils (similar to the sharks that swam 100

mil yr ago) Well developed caudal fin

› Heterocercal- upper lobe is longer than the lower lobe

› First dorsal fin longer and almost triangular› Paired pectoral fins, large and pointy › 5-7 gill slits behind head› Lots of rows of teeth› http://animal.discovery.com/tv-shows/other/videos/spy-on-

the-wild-basking-shark.htm

› http://www.youtube.com/watch?v=EukudEBC_hY

More sharksHammerhead sharks (sphyrna)Sawsharks (Pristiophorus)Size varies

Pygmy sharkWhale shark

found in tropical waters, are filter feedersBasking sharkGreat WhiteBull shark may live in riversSeveral sharks are only found in deep waterShark meat is eaten round the world and overfishing

is common

Sharks still fished for oil and skin and fins used for soup in the Orient

Rays and Skates

450-550 species Dorsoventrally flattened bodies

demersal - fishes that live on the bottom

Have gills on their underside (located ventrally) Stingrays:

Many species have a whiplike tailFeed on clams, crabs, small fishes and small

animals in sediment

http://www.youtube.com/watch?v=ufxGw8EqY5Q

Rays! Electric Rays have special organs,

that produce that produce electricity on both sides of their head› Romans and Greeks used them to help

headaches and other ailments  

Skates and Ratfish Skates lay egg cases The larger species are hunted by humans for

food Similar to rays in appearance and feeding but

lack whip like tail and spines

Ratfishes deep water fish, cartilaginous Feed on bottom dwelling crustations and

mollusks  http://www.youtube.com/watch?v=yCsa-YLTQVQ

Bony fishes Have cycloid or ctenoid scales - are flexible, thin, and overlap

cycloid scales- smoothctenoid scales- have many spikes on the exposed borders The scales are made of bone, covered by a thin layer of skin and a

protective layer of mucus

They have an operculum- a gill cover which is a flap of bony plates and tissue that protects the gills

The upper and lower lobes of the caudal fin are generally the same size (homocercal )

Mouth is terminal (located at the anterior end )Jaws are protrusible, b/c they can be projected outward from

the mouthHave a swim bladder- gas filled sack, just above the stomach

and intestines allows fish to adjust its buoyancy to keep it stable, compensates for

bone skeleton

Biology of fish Ichthyology- study of fishes Body shape is directly related to it's lifestyle

› fast swimmers have a streamlined shape› Laterally compressed seen on many inshore fish› Many demersal fishes are dorsoventrally flattened

some are laterally flattened

› eels-like fishes - distinctly elongated› slow fish- elongated vertically, triangular and

truncate or round› And random shapes› Body shapes can be used for camouflage

Colors!! Chromatophores - cells where pigments are found structural colors- result when a special surface reflects

a certain type of light › Mostly because of crystals that act like little mirrors

Some change colors with mood, or reproductive condition › used to advertise that they're dangerous, taste bad, poisonous

know as warning coloration,

Disruptive coloring- the presence of color stripes, bars or spots used to break up the outline of the fish› common in coral reef fish

Open water and shallow water fish are rarely as colorful Deep water fish tend to be either black or red, both are

extremely hard to see in the deep ocean  

Fishies moving! Swimming, its needed to... feed, reproduce, escape, to

get water through their gillsSwimming types….

Swim with side to side motion of either the body or the tail S-shaped contractions produced by bands of muscle called myomeres, which run along the sides the body, attached to the back bone for support Sharks tend to sink, to fix this they have large stiff pectorals

that provide liftOil rich liver

Skates and Rays use the pectoral fins to provide the lift Bony fishes have more maneuverability because of swim

bladder Dorsal and anal fins are used as rudders and provide stability

Some fish like tuna just use sheer speed

Fish eat too!!! *cue gasp*most sharks are carnivores

Nurse sharkCookie cutter shark

Lots of cartilaginous fish are filter feedersfilter water with gill rakers- slender projections on the inner surface of the gill arches

Digestionfood passes through the pharynx through the esophagus and into the stomach

stomach is typically J-shaped or elongated

Food then passes into the intestines Other enzymes are secreted in the walls of the inner walls of the digestive track and

in the pancreas

Liver secretes bile needed to down fatCarnivorous fish have short straight intestines Fish that eat seaweed have coiled intestinesThe intestines of cartilaginous fishes contain spiral valve which increases the

internal surface area of the intestine the intestine is responsible for absorbing nutrients

Undigested material passes through the anus or the cloaca

Circulatory system! All fishes have a 2 chambered heart that is located

below the gills › Sharks have to swim constantly to keep their heart

working Nurse shark doesn't have to do this (uses mouth opening and

closing to force water through their gills)

› In cartilaginous fish every gill lies in its own chamber and each chamber opens to the outside through a separate gill slit The 1st pair of gill slits is modified into spiracles- a pair of round

openings just behind each eye, located on the dorsal surface of skates and rays

Bony fishes: gills on each side share a common gill chamber that opens to the outside, each opening is covered by an operculum, when the mouth opens the opercula close and the pharynx expands, sucking water in. when the mouth this process is in reverse

 

And now, fish breathing! Gill arches support the gills and each arch

has 2 rows of fleshy projections called gill filaments,› Have a red ish color › Each gill filaments have many rows of thin

plates called lamellae (they contain capillaries) Surface area

The gas exchange Diffusion will only happen if oxygen is more

concentrated in the water than in the blood countercurrent system of flow- the blood

in the gills flows the opposite way as the water once the oxygen has entered the blood it is

carried through the body by hemoglobin, which is a red protein. It is contained in erythrocytes › Muscles also have myoglobin which is similar to

hemoglobin.

Internal environment

Blood of bony fishes less salty than› Lose water by osmosis, “drink” a lot of water.

Salt is extracted by kidneys and chloride cells in the gills. Small concentrated amounts of urine.

Cartilaginous fishes making their blood concentration closer to the concentration of seawater.› Retain a chemical called urea, amount in blood is

controlled by the kidneys. › “drink” water › Salts are excreted by kidneys, intestines and

special gland near anus called rectal gland.

The brain and eyes…

Vertebrates have most complicated and advanced nervous systems › Central nervous system, brain and spinal

chord coordinates body activities and stores

information.› Olfactory sacs, on both sides of the head,

used to smell, Each sac opens to the outside through 1 or 2

openings (nares)

EYYES! And tongue too Have LOTS of taste buds- located in

their mouth, lips, fins, and skin. › Found on barbels in many bottom feeders.

Eyes- focuses by moving closer or further away from the subject› bony fish depend more on eyesight than

cartilaginous fish. Bony fish have colored vision, cartilaginous fish

have none or vary little Some sharks have a nictating membrain

Navigation and hearing Lateral line- detect vibrations in the water,

system of small canals that runs along head and body, filled with sensory cells (neuromasts) that are sensitive to vibrations.

Cartilaginous fishes have ampullae of Lorenzini that can detect weak magnetic electrical fields.

Fish also have inner ears- paired hearing organs located to the sides of the brain, just besides the eyes.

Set of fluid filled canals that contain sensory The swim bladder can amplify sound. Gives equilibrium and balance. Detect changes in body position from movement of

calcareous ear stones or otoliths that rest on sensory hairs