Parts of a Fish

FINS     show

Fins come in a great variety of shapes and sizes. Their motion, sizes, shapes, and location allow different fishes to have varying degrees of swimimng speed and manueverability. Fast swimmers such as the tunas have streamlined bodies and fins that move relatively little. Others such as the remoras have highly modified fins for unusual purposes – like sticking to the sides of sharks, whales and other large animals.

Explore the diagrams to find out more. We can only show a fraction of the variety that exists.

Single (unpaired) fins

Unpaired fin: Caudal fin (tail)

 Zoom Shortnose Sturgeon
Acipenser brevirostrum Provided by New York State Department of Environmental Conservation. All rights reserved.
Tail shape is related to swimming speed and activity. The fastest fish like the tuna have lunate tails.

•  Interactive diagram
    Types of fish tails
   (caudal fins). •  Caudal fins and swimming speed

Unpaired fin: Dorsal (back) fin

 Zoom Oceanic Whitetip Shark
Carcharhinus longimanus Photographer - Michael Aston,

http://www.flickr.com/photos/
michaelaston/ CC BY-NC 2.0

Unpaired fin: Anal fin

 Zoom Fathead Minnow
Pimephales promelas Provided by New York State Department of Environmental Conservation. All rights reserved.

Paired fins

Paired fins: Pectoral fins
(homologous or equivalent to arms)

 Zoom California Sheephead
Semicossyphus pulcher Photographer - Memorie Yasuda.

•  Pacific Albacore
   Thunnus alalunga

Paired fins: Pelvic fins
(homologous or equivalent to legs)

 Zoom Largemouth Bass (upper)
Micropterus salmoides &
Rainbow Trout (lower)
Oncorhynchus mykiss Artwork by Duane Raver, U.S. Fish and Wildlife Service.

•  Comparison of primitive
    vs. derived position •  Tripod Fish - video

Miscellaneous fins

 Zoom Yellowfin Tuna
Thunnus albacares Finlets on back of tuna. Photo courtesy NOAA.

•  Finlets •  Adipose fin

SKELETAL & OTHER HARD MATERIALS     show

Coming in the future - Evolutionary significance of cartilage, bone, teeth and types of scales.

Bone, teeth, scales

Scales

 Zoom

The secrets of irridescence lie in the advanced crystal structure of this fish scale. Natural materials like this fish scale offer a wealth of ideas for materials of the future. Photographer - Chana Nudelman-Faust,
image courtesy Avital Levy-Lior [29].

Basics: •  Types •  Age and Growth •  Atlas-British Columbia,
    .pdf (easier to navigate) •  Atlas-British Columbia,
    web
Related stories: •  Fish scale analysis -
    Atlantic Salmon •  "Pearl essence"
    in paint, cosmetics, etc. •  Dermal denticles (sharks) •  Mega Fish Scales Inspire
    Future of Body Armor
    at MIT

Teeth

 Zoom Sheephead
Archosargus probatocephalus Photographer - Hank Brooks, VIMS Juvenile Fish Trawl Survey.

•  Pharyngeal teeth in cichlids

Skeleton

 Zoom Toothed Flounder
Cyclopsetta querna Radiograph courtesy California Academy of Sciences Dept. of Ichthyology.

•  California Academy of
    
Sciences Radiographs •  Digimorph Image Library

Otoliths (ear bones)

 Zoom Fish otolith
TBA
TBA Image courtesy Florida Fish and Wildlife Conservation Commission.
More about otoliths: • Wikipedia - Otoliths • Alaska Fisheries Science
   Center (AFSC)-
   Age and Growth Program • Otoliths: Morphology,
   Hearing, and Growth
How to sample: • 2005 Salmon Otolith
   Port Sampling Guide
Interactive • Age Reading
   Demonstration (ARD)
Image libraries: • AFSC Otolith Collection
   Database • A Guide to Otoliths
   from Fishes of the Gulf of
   Mexico and Atlantic Ocean
Related: •  Tiny otolith of Pygmy Goby •  Otoliths and Thermal Marking

 

CONNECTING INSIDE-TO-OUT     show

INTERNAL STRUCTURES & ORGANS     show

SENSORS     show

Before information about the external world can be analyzed on a computer, it must be detected by a sensor, collected and transmitted to a computer (or human note taker). In the same way, the sensory organs of fishes and humans must first detect motion, light, chemicals and other aspects of their environment before being transmitted through the nervous system to the brain for processing, and then acted upon.

Like instrumentation aboard an observational satellite, fish are loaded with various receptors that collect information such as sights and sounds. Major sensors are located on the head close to the brain. That information is used to initiate action — to capture prey, locate suitable mates, evade predators, and more.

Sensors include:

Motion detection

 Zoom Barred Surfperch
Amphistichus argenteus
Lateral line on the side of a Barred Surfperch marked by disruption in color pattern.

Barred Surfperch usually live in the surfzone of sandy beaches where people wade and swim. One of the few fishes that give birth to fully formed live young. Photographer and © Kip Evans.

Light detection

 Zoom Barreleye
Macropinna microstoma
Unusual transparent eye configuration of the Barreleye or Spookfish.
Image © The American Society of Ichthyologists and Herpetologists (ASIH). Permission granted by ASIH.
Image from "Macropinna microstoma and the Paradox of Its Tubular Eyes By Bruce H. Robison and Kim R. Reisenbichler, Copeia 2008, No. 4, 780-784.

Eye position and size are related to light levels and depth where a fish lives.

•  MBARI video - Barreleye

Electromagnetic field detction

 Zoom Great White Shark
Carcharodon carcharias
Electromagnetic field sensors lie at the ends of pores at one end of the Ampullae of Lorenzini on the snout of a shark. Photographer - © George T. Probst.

•  Electroreception •  Sharks' Sixth Sense
    Related to Human Genes?

Smell

 Zoom Redtail Catfish
Phractocephalus hemioliopterus
Photographer - Monika Betley.
Creative Commons 3.0
The barbels or "whiskers" of fishes such as catfishes are used to detect odors and locate food, even in murky water.

Fishes that return from the sea to the streams where they hatched navigate at least partially by recollection of smell.

•  5 Great Catfish Baits •  Investigations into how
    salmon find their home
    stream •  Do Salmon Navigate by the
    Earth's Magnetic Field?