General External Anatomy Medial Fins w Unpaired fins

General External Anatomy

Medial Fins w Unpaired fins with fin rays of bone or cartilage w Dorsal (one or more), caudal, anal w Some have adipose (no rays) – Salmonidae, Ictaluridae, Osmeridae

Variations are many

Paired Fins

Paired Fins w Pectoral fins - homologous to front legs w Pelvic fins - homologous to hind legs w Abdominal in position in more primitive fishes w Thoracic in position in more advanced fishes

Abdominal pelvics

Thoracic pelvics

Missing pelvics w Eels, ocean sunfish lack pelvics w Lampreys, hagfish lack pelvics, pectorals

Caudal fins

Heterocercal w Heterocercal - primitive fish like sturgeons, paddlefish, plus cartilaginous fishes w Superorder Chondrostei and Class Chondrichthyes

Modified heterocercal w Modified heterocercal - bowfin and gars w Superorder Holostei (bony ganoids)

Diphycercal w Diphycercal - lungfish and crossopterygians w Subclass Sarcopterygii (fleshy-finned)

Protocercal w caudal fin extends around the vertebral column w present in embryonic fish and hagfish

Hypocercal w Vertebral column extends into lower lobe w Fossilized ostracoderms (anapsids)

Homocercal w Vertebrae do not extend into a tail lobe w Fin more or less symmetrical w Pointed, rounded, truncate (squared), emarginate, forked, lunate

Body Shape

General Patterns

Rover-Predator w Streamlined (fusiform), stability and maneuverability produced by even fin distribution

Lie-in-wait Predator w Elongate, torpedo-like w Pointy head with teeth w Thrust generated by large caudal, posteriorly-located dorsal, anal fins

Surface-oriented Fish w Small, with upward-directed mouth and DV flattened head w Tend to have dorsal fin posterior w E. g. , mosquitofish

Bottom Rover w Flattened heads, fusiform to humped backs, enlarged pectorals, mouths terminal to inferior, barbels w Catfishes, sturgeons

Bottom Clinger w Small, with flattened heads, large pectorals, structures to hold to bottom in strong currents w Sculpin, gobies, clingfishes

Flatfish w Extreme flattening for life on bottom w Lateral – live on side – flounders, halibut w Dorsoventral – skates, rays

Rattail Fish w Large heads, pointy snouts, large pectorals, rat-like tails w Benthic deepsea dwellers w Genadiers, brotulas, chimaeras

Deep-bodied Fish w Laterally flattened, small mouth, short snout w Body depth > 1/3 standard length w Adapted for maneuverability

Eel-like Fish w Elongate bodies adapted for entering holes, crevices w May be missing paired fins w Eels, loaches

Body Shape

Scales

Types of scales w Placoid w Ganoid w Elasmoid (bony ridge) w Cycloid w Ctenoid

Class Chondrichthyes w Skin contains placoid scales w Similar in structure to teeth w Dentine-like core surrounded by enamel-like covering

Class Chondrichthyes

w Skin of most bony fishes is covered with mucous glands and embedded dermal scales

Class Osteichthyes w Ganoid or rhomboid scales (ganoin) w Heavy, diamondshaped, nonoverlapping w Primitive fish like gars

Class Osteichthyes w Cycloid scales roughly circular w Thin, flexible, overlapping w Modern bony fishes such as minnows, suckers, trout

Class Osteichthyes w Ctenoid scales - with minute ctenae or teeth - roughly rectangular w Thin, flexible, overlapping w Modern bony fishes such as sunfishes, perches

Class Osteichthyes w Fish growth is reflected in scale growth w Larger fish have larger scales w Scales continually growing temperature dependent

Class Osteichthyes w Able to determine age of fish in areas with winter - greatly reduced growth w “Rings” get closer together and form bands

Barbels

Barbels w Found in fishes in many groups w Catfishes w Loaches w Sturgeons w Minnows w Others

Catfishes

Loaches

Sturgeons

Minnows

Hagfishes

Cod

Barbels w Slender tactile organs near the mouth w Taste buds – used to search for food in murky water w Maxillary, nasal, mandibular or mental (chin)

Mouths

Gill Openings – single operculum

Gill Openings - 5 -7 slits

Gill Openings - 7 pores

Gill Openings

Oxygenated H 2 O Intake (spiracles)

Nostrils

Nostrils

Nostrils

Lateral Line