F ISHES Bio II Rupp

T YPES OF F ISHES Jawless Cartilaginous Bony

F ISH C HARACTERISTICS 4 hallmarks of chordates Sharks Lateral line Ampullae of Lorenzini Operculum Gills Tail types Scale types Fish musculature Swimming and the swim bladder

T AXONOMY Kingdom Animalia Phylum Chordata Subphylum Vertebrata

C LASS M YXINI Hagfish

C LASS C EPHALOSPIDOMORPHI Lampreys

C LASS C HONDRICHTHYES Sharks, skates, and rays

C LASS A CTINOPTERYGII Ray-finned fishes

C LASS S ARCOPTERYGII Lobe-finned fishes

C HORDATE H ALLMARKS Notochord Hagfishes and lampreys keep this their entire lives Made of thick-walled and fluid-filled cells pressed closely together

C HORDATE H ALLMARKS Dorsal hollow nerve cord Neural tube formation Anterior becomes the brain

C HORDATE H ALLMARKS Pharyngeal gill slits/pouches

C HORDATE H ALLMARKS

F ISH D EFINITION For our purposes: A gill-breathing, poikilothermic (cold-blooded), aquatic vertebrate that possesses fins and a skin that is usually covered in scales Approximately 25,000 species Two basic body forms Agnathans—jawless Gnathostomes—jawed

A GNATHANS Cephalospidomorphi—lampreys—ectoparasites Myxini—hagfishes—scavengers

S UPERCLASS G NATHOSTOMES Cartilaginous fishes Class Chondrichthyes—approx. 850 species Subclass Elasmobranchii—sharks, skates, and rays Dogfish anatomy

D OGFISH A NATOMY

G NATHOSTOME A DAPTATIONS

G NATHOSTOME R EPRODUCTIVE S TRATEGIES Internal fertilization Oviparous—some species lay eggs immediately after fertilization Ovoviviparous—retain the developing young in the uterus and they are nourished by yolk sacs Viviparous—young are nourished by a placenta

S UPERCLASS G NATHOSTOMES Bony fishes, aka osteichthyes Class Actinopterygii—ray-finned fishes Class Sarcopterygii—lobe-finned fishes

O STEICHTHYES A DAPTATIONS Operculum Tail types Skin and scales Musculature Swimming Swim bladder Gills

O PERCULUM A bony plate attached to a series of muscles running over the gills Aid in more efficient respiration Bernoulli’s Principle of Fluid Dynamics

T AIL T YPES

S CALE T YPES Scales are embedded in the dermis and covered by the epidermis Types Ganoid Cycloid Ctenoid Placoid

G ANOID SCALES

C TENIOD SCALES

C YCLOID SCALES

P LACOID SCALES Typical in sharks

F ISH M USCULATURE Myomeres-segments of the muscle Myospeta—division point of the myomeres Vertical septum and horizontal septum of body cavity

F ISH M USCULATURE Red muscle or dark muscle is used in regular swimming Red muscle is dark due to extra myoglobin and extreme vascularization Red muscle is often referred to as the bloodline White muscle for escape response

S WIMMING Short muscular bodies and lunate tails for most efficient swimming

S WIM BLADDERS Maintain neutral buoyancy and depth control Balloon-like structure Pulls gas out of the water to inflate Two types Attached to gut— ancient fishes Detached from gut— more modern fishes Fish without swim bladders: tuna, flounder, sharks, deep ocean fish Sharks have a huge fatty liver to maintain neutral buoyancy

G ILLS Made of filaments called lamellae Rich with blood vessels Covered by operculum or gill slits Counter current blood flow of blood and water increases efficiency— demonstration Gill arches are the point of attachment for lamellae Gill rakers remove debris from gills Larger gill surface is often correlated with higher fish activity levels