Fishies

Fishies

1. Structures

   • Fins
     • To be an actual fin, it must be supported by fin rays. 
     • Adipose Fin
       • Not truly a fin because it doesn't have any fin rays - it's just fatty tissues. 
     • Dorsal Fin
       • Most fish have one dorsal fin, some have 2, and some have none. 
     • Caudal Fin
       • Caudal Peduncle
         • Attachment of caudal fin to the body. 
       • Homo/Heterocercal tail
         • Homocercal: this term means that each half of the tail is the same height Heterocercal: one lobe of the tail will be larger than the other. 
     • Fin Ray vs Spine
       • A fin ray is quite flexible, while a fin spin is very hard, thick, and larger than a fin ray. 
       • Dorsal Spines
         • Do not have "fin" attached to them and are used for protection against predators.
   • Gills
     • Fin breathe in through the mouth, which draws water over the gills, where gas exchange takes place. 
     • Operculum
       • The operculum covers the gills - the fish is able to open or close to operculum to breathe out the water it pulled in through its mouth. 
   • Lateral line
     • Not just a line of colour. Each dot on the line is a sensory organ, and the lines are unique to species - may be straight, wiggles, arched, etc. The configuration can be used to ID fish. Fish use this line to sense differences in pressure in the water around them and differences in electrical potential - muscle movement. Essentially, using the lateral line they can feel other organisms moving around them. 
   • Mouth
     • Terminal
       • Mouth is right at the end or terminus of the head/tip of the snout. 
     • Upturned
       • Not terminal - directly slightly upward. Generally, any fish with an upturned mouth spends most of its time at the surface of the water, eating things off the surface. 
     • Subterminal
       • Slightly below the terminus of the snout and pointing downward. 
     • Ventral/Underslung/Inferior
       • Mouth is directed STRAIGHT DOWN. More obvious than just subterminal. 
   • Ctenoid scales
     • Soft and the "typical" fish scales.
   • Ganoid Scales
     • Much tougher scales that are more armour like.
   • Barbel
     • Barbels are "whiskers" of fish - they aren't made of the same material as mammal whiskers and are simply fleshy projections. 
   • Bony Armour
     • Plates instead of scales can seriously armour a fish. 

2. Aquatic Fieldwork

   • Nets
     • The size of the netting more or less will determine what's important or what we want to catch. Aquatic nets are usually very heavily built with a thick steel frame and the bag itself is reinforced.
     • Flat bottomed
       • These are triangular and typically very useful for working along the surface of the body of water.
   • Water Quality
     • Temperaure, dissolved solutes, ph, etc.
     • Secchi Disk
       • This is a measure of turbidity. You lower it down until you can't see it, then raise it till you can, and then you average these two heights.
   • Surber Sampler
     • Placed on the bottom with a metal box that fits into the much. You stir up the muck and try to accumulate organisms. Once you've stirred up the organisms in that square, it standardizes your estimations of what lives in that area. White pans are important because it is easiest to see most organisms against a white background.
   • Dyanmite
     • Used to be used. Kills fish underwater and when they all float to the top you can asses what lives there.
   • Rotenode
     • This is  fish specific poision that is usually used to kill off the population so you can replace it with a more attractive fish species.
   • Seine
     • Large net curtain with a lead line on the bottom that keeps it down, which drastically improves the amount of fish you're able to catch.
   • Nesting Boards
     • Fish like to put their nests on the undersides of boards on the plastic undersides. Females go away and live fish live and males will guard the eggs. You can count the eggs/clutches by simply flipping the board over and looking.
   • Gee traps
     • Specific brand of minnow trap that is simply a cage suspended from a float in a lake.
   • Clove oil
     • Clove oil renders fish unconscious without killing or harming them

3. Stickleback minnow

4. Flathead minnow