Glossary/Visuals

*There are three sections within this page:

1) Glossary Terms 2) Fish Illustrations 3) Web/Book Resources

 

Glossary Terms

  • Abdomen – Fish’s belly (Between pelvic fins and anus of the lower side of the fish)
  • Adhesive – Referring to eggs, those who stick to one another or a substrate after water hardening
  • Adipose fin – small fin without rays located on the fish’s back between the dorsal fin and the tail
  • Air or Swim Bladder – A balloon-like organ located in the gut of the fish that is either used for respiration or to control buoyancy
  • Alevin – A newly hatched fish that still has its yolk-sac
  • Anus – The external opening of the intestine, the vent
  • Anal fin – one fin located on the bottom of the fish near the tail
  • Bands – horizontal marks running lengthwise along the side of a fish
  • Bars – Vertical markings on the side of the fish
  • Barbel – thread-like sensory structures on a fish’s head by the mouth, “whiskers”
    • Used for taste and smell
  • Branchiostegal Rays – Bony rays supporting the membranes which close the gill cavity under the head
  • Bristle – A stiff hair-like projection
  • Carnivore – feeds on other fish or animals
  • Caudal fin – tail fin
  • Caudal Peduncle – body portion found between anal fin and beginning of the tail
  • Caudal Spot – Spot on base of the caudal fin
  • Chevron-shaped – Earliest developmental form of myomeres in larvae (angle formed by the epaxial and hypaxial portions of the myosepta)
  • Chromatophore – A modified dermal cell that contains pigment that provide fish with color
  • Chorion – The outermost membrane of a fish egg after water hardening
  • Compressed – Flattened from side to side
  • Copepod – small crustacean (zooplankton community)
  • Ctenoid – Scales having small, needle-like projections on the posterior area
  • Crustacean – Aquatic species that have paired antennae, jointed legs, and exterior skeleton
    • Common food for most fish (crayfish, water flea, crabs, etc)
  • Dorsal – top of fish or near the back
  • Dorsum – The upper (dorsal) surface of the head or body
  • Drainage – A group of lakes or streams within a basin (Ex: Lake Michigan)
  • Epaxial – The portion of the body above the horizontal myoseptum
  • Fin Base – Part of the fin attached to the body
  • Finfold – Median folds that are a tough protective layer on the outside of their skin
  • Forked – With the caudal fin, the rear edges are distinctly indented
  • Fusiform – Cylindrical and tapering at both sides of the body
  • Genus (plural: genera) – Taxonomic category including one species or a closely related group of species (sharing a common ancestor)
  • Gills – Organs used for aquatic respiration
  • Gill Cover – (Opercle or Operculum) Bones covering the gills
  • Gonads – Sexual organs that produce eggs or sperm
  • Habitat – Environment where a fish lives
  • Herbivorous – Plant-eating fish
  • Hypaxial – The portion of the body below the horizontal myoseptum
  • Hypolimnion – In a thermally stratified lake, it is the bottom layer of the lake (depleted of oxygen by decaying water)
  • Ichthyologist – A scientist who studies fish
  • Inferior Mouth – Snout projecting beyond the lower jaw
  • Invertebrates – Animals without backbones (Insects, crayfish, earthworms, leeches, etc)
  • Invasive – Non-native species within a specific geographic location
  • Juvenile – Young (small version of adult) fish that has developed complete fin ray development and finfold absorption to be sexual mature
  • Keel – Shelf-like fleshy or bony ridge
  • Larva (plural: larvae) – Newborn; developmental stage of fish before it becomes a juvenile
  • Lateral – Side of fish
  • Lateral Line – A series of pored scales along the side of a fish that contain organs which can be used to detect vibrations
  • Lateral Scale-Count = Number of scales along lateral line
  • Lateral Scales – Row of scales along the side (middle) of fish (gill cover to base of caudal fin)
  • Littoral Zone – Spawning habitat (less than 15 feet deep) for freshwater fish that also holds the majority of aquatic plants in lakes
  • Mandible – Lower Jaw
  • Maxillary – Upper Jaw
  • Melanophore – A dark brown or black pigment (cells containing melanin) (pepperlike dots)
  • Mollusk – An invertebrate with a soft and smooth body (clams)
  • Morphology – Form or structure of an organism
  • Myomeres – Body segments
  • Myoseptum – Thin partition of connective tissue which joins myomeres
  • Nape – Upper surface of the body behind the head and before the dorsal fin
  • Nares – Nostrils
  • Native – An indigenous species
  • Omnivore – A fish that eat both animal and plant matter
  • Origin – Point where the fin begins
  • Otolith – Ear bones (calcareous structures)
  • Paired Fins – Pectoral and pelvic fins
  • Pectoral Fins – paired fins on the side of the fish (behind the head/gills)
  • Peduncle – Fleshy end of the body between the anal and caudal fins
  • Pelvic Fins – paired fins below the pectoral fins on the bottom or ventral portion of the fish
  • Perivitelline space – Fluid-filled space between the chorion and yolk material
  • Piscivore – A predator fish that mainly eats other fish
  • Pharyngeal Teeth – Bony tooth-like projections derived from the fifth gill arch
  • Planktivore – A fish that feeds on plankton
  • Plankton – Small plants (phytoplankton) and animals (zooplankton) mostly free-floating
  • Plicae – Wrinkle-like folds found on the lips of some catostomids
  • Pore – Tiny opening in the skin
  • Postanal Length – Distance from the most posterior point of the anus to the most posterior point on the caudal fin or median finfold
  • Postanal Myomeres – Number of whole myomeres posterior to an imaginary vertical line at the most posterior point of the anus
  • Preanal Length – Distance from the most anterior point on the snout to the most posterior point on the anus
  • Preanal Myomeres – Number of myomeres from the nape to an imaginary vertical line at the most posterior point of the anus
  • Ray – Flexible, branched segmented fin. (Bony element that supports and spreads membranes)
  • Redd – A nest-like depression made by either males or females during spawning
  • Roe – Fish eggs
  • Scales – small, flat plates covering the outer skin of fish
  • Silt – small disturbed bottom particles (smaller than sand but bigger than clay)
  • Snout – Portion of the head in front of eyes and above a mouth
  • Spawning – The process of fish reproduction (Females lay eggs while males fertilize them)
  • Spine – Hard, unsegmented and unbranched ray in fin (Spinous ray)
  • Spiracle – An opening on the head above and behind the eye that is a canal leading to gill chambers in bony fish
  • Spot – Circular color marks
  • Standard Length – Length of the fish from the mouth to the end of the vertebral column (before the tail (caudal fin))
  • Stripe – Horizontal band of color
  • Subspecies – Geographically diagnosable population of a species
  • Substrate – Bottom composition of water bodies (lake, river, streams, etc)
  • Subterminal – Mouth opens below foremost point of head (Mouth Position)
  • Superior Mouth – Condition when the lower jaw extends upward and the mouth opens dorsally
  • Tail – Portion of the body posterior to the anus (Larvae)
  • Teleost – Large group containing most of the bony fish
  • Thermocline – The middle layer of a stratified lake which is oxygen-rich and characterized by its sharp drops in water temperature
  • Terminal Mouth – Condition when the lower and upper jaws are equal in length and the mouth opens terminally
  • Territorial – Defending of a particular area
  • Total Length – Length of fish from the mouth to the tail
  • Tributary – Stream that feeds into another water body
  • Turbid – Water cloudy by suspended solids or plant matter (limits visibility and sunlight penetration)
  • Urostyle – Final vertebral segment usually modified for caudal fin support
  • Ventral – Underside of fish
  • Vertebrate – An animal with a backbone
  • Water Hardening – Process of membrane delamination and fluid formation which forms the perivitelline space
  • Yolk – Part of the egg that contains food for developing fish
  • Yolk Sac – Ventral extension of the gut containing yolk
  • Yolk Sac Larvae – Phase of development from hatching to complete absorption of yolk
  • Zooplankton – tiny animals that float or swim weakly that are a common food for small fish

 

Illustrations of Fish Morphology

*Click on the visual to better understand and identify physical characteristics of fish.*

Physical Characteristics of Freshwater Fish in Wisconsin (WIDNR)

Physical Characteristics of Freshwater Fish in Wisconsin. DNR.

 

Fish Anatomy Illustrations

*Click on visual to learn more about their body forms, coloration patterns, fin types, and mouth morphology.*

Fish Anatomy Categories to Identify Fish (UW – Sea Grant)

Fish Anatomy Categories to Identify Fish. UW – Sea Grant.

Glossary Book Resources

  • Auer, N. A. (ed.). 1982. Identification of larval fishes of the Great Lakes basin with emphasis on the Lake Michigan drainage. Great Lakes Fishery Commission, Ann Arbor, MI 48105. Special Pub. 82-3:744 pp.
  • Bosanko, Dave. 2007. Fish of Wisconsin – Field Guide. Adventure Publications, Inc. Cambridge, MN. Print
  • Burr, B & Page, L. 2011. Peterson – Field Guide to Freshwater Fishes. Houghton Mifflin Harcourt Publishing Company. New York, NY. Print.
  • Becker, George. Fishes of Wisconsin. University of Wisconsin, Press. Madison, WI. 1983. Print.