Fish

History First vertebrates 500 m.y.a. Fish are the most economically important marine organism Fertilizer, feed, protein

Classification Kingdom- Animalia Phylum- Chordata Sub Phylum- Vertebrata (backbone) Classes- Agnatha Chondrichthyes Osteichthyes

Vertebrates Four fundamental characteristics Backbone (vertebrae/spine) Nerve cord (spinal cord) Protected by vertebrae Skull Bilateral symmetry

Classification Kingdom- Animalia Phylum- Chordata Sub Phylum- Vertebrata (backbone) Classes- Agnatha – jawless fishes Chondrichthyes – cartilaginous fishes Osteichthyes – bony fishes

Agnatha Jawless fish: Lampreys, Hagfish

AGNATHANS Jawless fish - agnatha Oldest group – very primitive Scale-less skin Some Parasitic / some filter feed Circular mouth with fleshy teeth Cartilaginous skeleton

Types of Agnathans Hagfish - Scavengers, not much known about them. Lamprey- fresh and salt water; parasitic and prey on other fish. * Both have cartilaginous skeletons and sucker-like mouths.

Chondrichthyes Cartilaginous Fish: Shark, Ray, Skate, Chimaera

CHONDRICHTHYES cartilaginous fish condrichthyes Skeleton made of cartilage Sharks, rays, skates All are predatory except 4 species!

The 4 exceptions are filter feeders Whale sharks – warm shallow water THE LARGEST FISH IN THE SEA!!!

The 4 exceptions are filter feeders Basking sharks – cold shallow water THE SECOND LARGEST FISH IN THE SEA!!!

The 4 exceptions are filter feeders megamouth shark – cold deep water

The 4 exceptions are filter feeders manta ray– shallow warm water

Chondrichthyes Sharks adapted for a predatory lifestyle. Hydrodynamic body (fusiform) Stiff pectoral fins (speed). Have live births. Placoid scales. Mantas, Sting Rays live in shallow water, have mouths located on the underside, fairly docile, wide flat bodies and wing-like fins that are flexible.

Types of Chondrichthyes Sharks and Rays No operculum and must keep moving to breathe. Placoid scales that feel and look more like sandpaper. Skeletons made of cartilage not bone.

Types of Chondrichthyes Chimaeras No operculum and must keep moving to breathe. Scaleless Bottom feeders Longnose chimaera has a venomous spine

Chondrichthyes - SHARKS Fusiform body shape Caudal fin = heterocercal 2 dorsal fins Paired pectoral fins ‘conveyor belt’ teeth Cartilaginous skeleton

Chondrichthyes - SHARKS SPECIALIZED BODY PARTS Extra oily liver for buoyancy Lateral line Ampullae of lorenzini Keen olfactory & optical senses

They get a Bad Rap :-( Watch “Planet in Peril: Battle Lines”

Species

Osteichthyes Bony Fish: Salmon, Carp, Tuna Over 20,000 different species

Types of Osteichthyes Ray Finned: Lobe Finned: Most fish Fins are supported by bony structures called Rays. Teleosts are the most advanced (homeocercal tails and mobile fins). Lobe Finned: Fins are long, fleshy, muscular, supported by central core of bones. possible ancestors of amphibians. Examples are: Coelacanth, Lungfish

Fish Characteristics Gills Backbone Paired Fins Single Loop Circulation Two chambered heart

Fish Anatomy

Fins

Different Dorsal Fins

Fish Respiration Water flows over gills as fish opens mouth and swims. Water flows opposite direction of blood flow. O2 diffuses from the water into the blood. Gills are made of thousands of gill filaments. Gills are covered by the Operculum.

Up Close and Personal

Fish Circulation Fish heart has 2 chambers Single loop circulation Blood flows into gills, picks up O2, goes to the body, returns to the heart.

Fish Reproduction Most Fish reproduce sexually, and fertilize their eggs externally (Sharks-internally). Spawning is the process of fertilizing eggs. Baby fish are called FRY.

Fish Adaptations Lateral Line System- used to detect vibrations, orient the fish in water, it is a line of cells running down the side of the fish. Operculum- gill cover, movement of operculum allows more water to be drawn in. Swim Bladder- a gas filled sac that helps the fish maintain buoyancy. Sharks don’t have a swim bladder! Fins- Dorsal, Caudal, Pectoral, Pelvic, Anal.

Adaptations Air Bladder Operculum Lateral Gills Line Fins

Body forms of fishes 1. fusiform Sharks, tuna, bluefish Streamlined, torpedo shaped Fast long distance swimmers Open water predators

Body forms of fishes 2. compressed Perch, butterfly fish, angelfish Flattened laterally Quick bursts of speed - short distance Easily move in tight spaces

Body forms of fishes 3. depressed Flounder, fluke, stingray Dorso-ventrally flattened Live on the bottom Eyes on top of body

Color Can be an important identifying characteristic when dealing with live specimens. There may be no color in preserved specimens Color varies with habitat Color varies between males and females especially during breeding season Color patterns can be important. Vertical bars versus Horizontal stripes.

Body forms of fishes 4. attenuated Eels, lamprey, pipefish Elongated, tubular shape Many Live in holes / burrows Many secrete heavy mucus

Other Morphological Characteristics Mouth Position Mouth position is not only a good identifying characteristic but it also tells you something about what the fish eats and where you would likely find it in the water column. Taken from: Helfman et. al. 1997, The Diversity of Fishes

Other Characteristics Morphometrics and Meristics Morphometrics are things you can measure length of snout, eye diameter. Meristics are things you can count number of anal fin rays, scales above the lateral line

Body parts of fish Get ready to draw a fish!!!

1. Caudal fin - tail fin Used for forward motion and acceleration

Singular fins 2. Dorsal fin & 3. Anal fin Used to prevent rolling/tipping

4. pectoral fin & 5. pelvic fin paired fins (left & right) 4. pectoral fin & 5. pelvic fin Used to balance, stop & turn

6. Spines Used for protection Some contain poison sacs

7. operculum Covers & protects gills Not found in sharks

8. Lateral line Sensory canals used to detect changes in water pressure around the fish (similar to human ear)

Lateral Line and schooling

COMPARISON OF CARTILAGINOUS & BONY FISHES TRAIT CARTILAGINOUS BONY_____ TUNA, COD, SALMON, SHARKS, RAYS, SKATES EXAMPLES SKELETON CARTILAGE BONE ABSENT – OILY LIVER PROVIDES BUOYANCY PRESENT – AIR FILLED FOR BUOYANCY SWIM BLADDER

COMPARISON OF CARTILAGINOUS & BONY FISHES TRAIT CARTILAGINOUS BONY_____ EXTERNAL – LAY MILLIONS OF SMALL EGGS INTERNAL – HAVE FEW LARGE YOUNG IN LIFE TIME FERTILIZATION SCALES PLACOID – SPINY EMBEDDED IN SKIN GANOID – PLATELIKE CTENOID & CYCLOID ARE FLAT, FLEXIBLE, OVERLAP

COMPARISON OF CARTILAGINOUS & BONY FISHES TRAIT CARTILAGINOUS BONY_____ HAVE OPERCULUM COVER & PROTECT GILLS GILLS NO OPERCULUM HAVE GILLS SLITS FEEDING BEHAVIOR ALL PREDATORS FOUR EXCEPTIONS GREAT VARIATION IN FOOD SOURCES RIGID AND UNSEGMENTED Heterocercal tail FLEXIBLE AND SEGMENTED Homeocercal tail FINS NOT FUSED TO JAW -REPLACEABLE TEETH FUSED TO JAW - IRREPLACEABLE