› Fishes are dated back to over 480 million years › Fish evolved in fresh water  Now fish live in ALL water areas – fresh and salt › Fish are the dominant, free-swimming animals of the seas. › Diet:  Some are herbivores (eat plant material)  Others are carnivores (eat meat material)

› The structure of the body is designed for ease of movement  This has enabled fishes to live in most parts of the world's water bodies › Come in all shapes and sizes › Active life style:  Some are free swimming,  While others rest on the bottom of the sea

 Fish Anatomy › Fins  Made up of stiff rays covered by skin.  Some may be jointed  Some separate near the edge of the fin.  Functions :  Each fin on a fish is designed to perform a specific function.

 Fish Anatomy  Fish Anatomy › Fins  Dorsal fin: lends stability in swimming, controls roll  Ventral fin: lends stability in swimming.  Caudal fin: main propelling fin, provides thrust and controls direction  Anal fin: lends stability in swimming, increase speed  Pectoral fins: Locomotion and side to side movement, acts as rudder and brakes or as feet (mudskippers)mudskippers

 Skin › Made of collagen and blood vessels. › The skin of fish is divided into two layers, the Epidermis (outer) layer and the Dermis.  The Epidermis is made of epithelial cells,  Constantly shed and replaced with new ones.  Between the epithelial cells are slime cells  Produce mucous secretions that form the very important protective covering (slime coat)  The dermis lies under the epidermis

 Swim Bladder › Helps maintain buoyancy in the water. › A sac inside the abdomen that contains gas.  Scales › Scales do not stick out of a fish › The scales overlap › Form a protective flexible armor › Capable of withstanding blows and bumping

 Lateral line system › Def—a series of scales, which connects with a system of canals containing sensory cells and nerve fibers › It runs in a semi-line from the gills to the tail fin › Seen as a band of darker looking scales running along the side › VERY important sensory organ in fish  It can detect minute electrical currents  Also functions to help the fish identify its surroundings.

 Swimming (Two types) › Cruisers: Swim continuously in search for food, such as the tuna. › Burst Swimmers: stay relatively in the same place (most reef fish)  Internal Body Temperature › Cold blooded (exotherms)  Derive their body heat from their environment and conform to its temperature

 Three Modes of Reproduction:  Three Modes of Reproduction: 1.Oviparous–  Lay undeveloped eggs,  External fertilization (90% of bony fish), Internal fertilization (some sharks and rays) 2.Ovoviviparous  Internal development- without direct maternal nourishment  Advanced at birth (most sharks + rays) 3.Viviparous  Internal development- direct nourishment from mother  Fully advanced at birth (some sharks, surf perches)

 In fishes, oviparous is most common  Parental care: › Parental care is very rare as most fish are broadcast spawners, but there are a few instances of parental care.  Methods of Parenting › Egg Scatters- scatter eggs on bottom › Nest Builders- arrange protection for eggs › Egg depositors- selectively place eggs › Mouthbreeders- house eggs in mouth › Egg buriers – bury eggs › Livebearers- give live birth

 Respiration › Gills  Located under the gill covers.  Five gill slits and four gill arches.  Gills are actually mounted/located on gill arches  Circulation › Heart only has two chambers, in contrast to our heart which has four. › Heart only pumps blood in one direction. › A very simple closed-circle circulatory system.

 Digestion › Some have a spiral valves in intestine (shark)  Slows food for better absorbtion › Most have complete system  Excretion › Oily liver to help with water retention, salt levels and excretory purposes

 Sensory › Fish can sense light, chemicals, vibrations and electricity. › Senses (in addition to lateral line)  1) Vision:  Vision underwater poses many special problems. The most significant is the small amount of light  Vision is limited to a few yards at best

 Senses, cont. › 2) Smell  Used in the location of food › 3) Hearing  It has been shown that fish can hear, but not very well › 4) Taste  Taste buds in fish are located in the mouth and also in the skin covering the head, body fins, and lips. › 5) Touch  Nothing of importance

 Senses, cont. › 6) Chemicals: › 6) Chemicals:  Some fish (such as sharks, rays, eels, and salmon) can detect chemical levels as low as 1 part per billion. › 7) Vibrations: › 7) Vibrations:  Do have ears located within their bodies  Also have lateral line system that actually lets them feel their surroundings. › 8) Electricity:  Sharks and rays posses special organs for detecting electrical potential [voltage].

› Kingdom Animalia › Phylum Chordata (Subphylum Vertebrata) › Fish Classes:  Modern fish are divided into three classes. 1.Superclass AGNATHA 2.Class CHONDRICHTHYES 3.Class OSTEICHTHYES

› The most "primitive" of the fishes; › Lack a jaw and a bony skeleton. › Very flexible › Smooth, scaleless skin and are soft to the touch. › In place of the jaws is an oral sucker › Many are highly predatory, attaching to other fish by their suckerlike mouths,

› Found in both fresh and salt water and some are anadromous  Def: living in both fresh and salt water at different times in its life cycle › The hagfish has no eyes, while the lamprey has well-developed eyes. › Cartilaginous and fibrous skeleton › Ex: Hagfish and Lamprey

› Members include the sharks, skates, rays, and ratfish. › Have cartilaginous skeleton, but their ancestors were bony animals. › These were the first fish to exhibit paired fins. › Pelvic fins in males are modified (claspers) used in copulation › Chondrichthyes lack swim bladders,

› Internal fertilization › posses 5-7 gill arches (most have 5). › Exposed gill slits › They have cartilaginous upper and loosely attached lower jaws with a significant array of teeth. › Their skin is covered with teethlike denticles which gives it the texture and abrasive quality of sandpaper. › Separate sexes with paired gonads › Cloaca › All modes of reproduction

› Comprise the largest section of the vertebrates, with over 20,000 species worldwide. This compares to 51,000 total vertebrate species. › They are called bony fish because:  Their skeletons are calcified, endochondral (start out as cartilage)  Makes them much harder than the cartilage bones of the chondrichthyes.

› Have great maneuverability and speed, › Have highly specialized mouths equipped with protrusible jaws › Pharyngeal jaws for chewing, grinding, crushing › Contain a swim bladder to control buoyancy. › Operculum covers gills › Live in most marine and freshwater habitats on earth. › Ex: perch, bass, bluegill, flying fish, sea horse, clown fish, catfishflying fish