Scales The Fish Scales – Made from bone and look like shingles The Shark Scales or Dermal Denticles – tiny toothe like structures – smooth and feel like sandpaper
Fins Move, Stabilize and Protect Paired – pectoral and pelvic Unpaired – anal, caudal, and dorsal Placement and purpose varies Bony fish – visible supporting rays and spines Cartilaginous – no visible support
Gills Oxygen enters at gills Found along the side of the head – Feathery in structure Appear bright red when healthy Sharks have 5-7 gill slits that allow water to pass out of the gill cavity Bony fish gills covered by a bony plate – the operculum
Eyes Most well developed Sharks – Pupils that dilate and constrict, eyelid that closes from the bottom up Fish – Lack both
The Mouth Location 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 Shapes Fusiform 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 speed Crescent-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.
Color Red – Common color in fish – deep water or nocturnal Countershading – Dark on top light on bottom Disruptive coloration – camouflage Eyespot – mimicry, spot usually near tail Warning Coloration- advertise defense mechanism Camouflage – blend into the background
Senses Sight – 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 buds Hearing – Inner ears are well developed and pick up sound waves through the fish’s body Lateral Line – Feel movements in the water Electricity – Some have special pores that detect electricity.
Several methods for getting around Waves passing down the body Flex the posterior (caudal) portion of the body Flap pectoral fins and (sometimes) tail Move just the tail