Fish Phylum Chordata

• Subphylum Vertebrata: Vertebrae surround nerve cord and serves as a primary support; skeleton modified into a skull for protection of the brain.

• This group includes fish, amphibians, reptiles, birds, and mammals • Notocord is replaced by a vertebral column.

• Superclass Agnatha: lack jaws and paired appendages; cartilaginous skeleton; persistent notochord

Pouch lamprey, hagfish, and lamprey eel

Other General Characteristics• - aquatic, scales, fins, and pharyngeal slits • Nervous system: well developed with brain and spinal

cord• Control smell, sight, body movement • Vertebral column for protection• Chemoreceptors

• Closed circulatory system –Heart ->ventricle->Aorta-> gills

• Excretory: Kidneys remove ammonia

• Respiration: Gills: water in mouth, through gills, and out through gill slits- exchange Oxygen and CO2• Some use lungs • Swim bladder- open space in fish to regulate buoyancy

• Feeding: • Herbivores, carnivores, filter feeders, detritivores, parasites • Pathway: Mouth->Esophagus->Stomach-> pyloric ceca-

>intestines->anus

• Reproduction: dioecious • Oviparous: lay eggs, external fertilization • Oviviparous: young develop in mom, but are not nourished

by mom • Viviparous- bare live young, nurtured by mom

Classes of Fish ***Correction!• A: Myxini- Hagfish • B. Chondrichthyes- Cartilagenous fish and sharks • C. Osteichthyes- bony fish , 40 % of all vertebrates are bony fish •D. Petromyzontida- lampreys

Classes of Fish • You will summarize the characteristics of the different

classes of Fish providing the following information: • For CLASSES MYXINI,PETROMYZONTIDA,

SARCOPTERYGII• 1) EXAMPLES• 2)MOUTH CHARACTERISTICS• 3)OLFACTORY SACS• 4)PHARYNGEAL SLITS (HOW MANY ? 1 OR MORE

OPENINGS?• 5)FEEDING HABITS

For classes Chondrichthyes and Actinopterygii • Examples• Digestion• Respiration• Skin• Skeletal system• Circulatory system• Swim bladder?• Movement (fins present and what kind?) • Reproduction methods

Characterisitics Class Myxini Class Petromyzontida

Examples Hagfishes LampreysMouth 4 pairs of tentacles Sucking mouth with

teeth and rasping tongue

Olfactory sacs Open to mouth Blind sacsPharyngeal slits 5-15 pairs; one

opening7 pairs; separate openings

Feeding Scavenge dead or dying fish; produce copious slime

Parasitic or predatory; feed mainly on blood

Characterisitics Chondrichthyes OsteichthyesExamples Sharks, skates, rays All bony fish

Digestion Complete, lack pyloric cecum, have a cloaca (a common opening for the reproductive, excretory and digestive systems)

Complete, have a pyloric cecum (used to increase absorption in the intestine)

Respiration Gills Gills covered by an operculum (helps pump water across the gills)

Skin Covered by placoid scales (feel sandpapery)

Covered by cycloid or ctenoid scales

Skeleton Cartilage endoskeleton Bony endoskeleton

Circulation Closed, two chambered heart; 1-loop (from heart past gills to the rest of the body and back to the heart)

Closed, two chambered heart; 1-loop

Swim bladder (gas filled sacs that regulate buoyancy)

Lacking Typically present

Temperature regulation Ectothermic Ectothermic

Lateral line system (used to detect movement in the water)

Present Present

Movement Paired fins (used for more precise steering and increase agility), heterocercal tail

Paired fins, homocercal tail

Reproduction Dieocious, internal fertilization, ovoviviparous, males have modified pelvic fins called claspers

Dieocious, variable fert.; some are oviparous, some are ovoviviparous