Fish Form and Function

Why does it look like that?

The Basic Fish

The Basic Shark

ScalesThe Fish

Scales – Made from bone and look like shingles

The SharkScales or Dermal Denticles – tiny toothe like structures – smooth and feel like sandpaper

FinsMove, Stabilize and ProtectPaired – pectoral and pelvicUnpaired – anal, caudal, and dorsalPlacement and purpose variesBony fish – visible supporting rays and spinesCartilaginous – no visible support

GillsOxygen enters at gillsFound along the side of the head – Feathery in structureAppear bright red when healthySharks have 5-7 gill slits that allow water to pass out of the gill cavityBony fish gills covered by a bony plate – the operculum

Gills and “Breathing”

EyesMost well developedSharks – Pupils that dilate and constrict, eyelid that closes from the bottom upFish – Lack both

The MouthLocation and Size can determine food and ecosystem.

Terminal – can chase and capture things or pick at things. Located on the front end

Up-Pointing: long lower jaw & feeds near the surface. The mouth opening is toward the top of the head.

Sub-Terminal: on the underside of the head, usually feed on the bottom.

Some fish have specialized mouths. The seahorse has a tiny mouth at the end of a straw-like snout that is used to "slurp"zooplankton.

The Sharks’ mouth is located on the underside of its head.

Body ShapesFusiform or streamlined - capable of swimming very fast, usually live in open water.

Laterally compressed: usually do not swim rapidly, exceptionally maneuverable.

Depressed: flattened from top to bottom (like stingrays) live on the bottom.

Eel-like: snake-like body shape

Some fish fit into no categories, they tend to have protective outer coverings and are slow swimmers.

Tails – indicate speedCrescent-shaped: Fish with crescent-shaped tails are fast swimmers and constantly on the move.

Forked: Fish with forked tails are also fast swimmers, though they may not swim fast all of the time. The deeper the fork, the faster the fish can swim.

Rounded: Fish with a rounded or flattened tail are generally slow moving, but are capable of short, accurate bursts of speed.

ColorRed – Common color in fish – deep water or nocturnalCountershading – Dark on top light on bottomDisruptive coloration – camouflageEyespot – mimicry, spot usually near tailWarning Coloration- advertise defense mechanismCamouflage – blend into the background

SensesSight – Most have good sight.Smell – nares are two blind sacs that detect odor.Taste – Taste buds are in lining of mouth and gills, Barbels are “whiskers” that are covered with taste budsHearing – Inner ears are well developed and pick up sound waves through the fish’s bodyLateral Line – Feel movements in the waterElectricity – Some have special pores that detect electricity.

Several methods for getting around

Waves passing down the bodyFlex the posterior (caudal) portion of the bodyFlap pectoral fins and (sometimes) tailMove just the tail

Getting Around