Lesson 4. – Fangs, Fins, Mouths, and Eyes Lesson Objectives: Students Will Learn What the Appearance of Fangs, Fins, Mouth and Eyes Can Tell a Researcher

FISH ECOLOGY Lesson 4. – Fangs, Fins, Mouths, and Eyes Lesson objectives: Students will learn what the appearance of fangs, fins, mouth and eyes can tell a researcher. Students will see examples of each.

Vocabulary words: canine, krill, plankton, subterminal, terminal, nictitating, caudal, dorsal and ventral How do Fish Teeth Differ?

Many fish have teeth on several them as predators that can head and face bones. Some take large bites and swallow fish do not have 'teeth' at all, prey whole. Sharks have rows they are merely extensions of of teeth that allow them to take the bones in their heads that bites out of prey that are too big are used for feeding. Other fish to swallow. Barracudas and have teeth on the tongue and piranhas also have the same between the gills. Some fish dental arrangement. Deep-sea have plate-like teeth that are fish have dagger-like teeth that used for grinding corals, and help them to grasp prey of large crushing shells to get to the size and hold it until it can be softer prey beneath. Other fish swallowed. have strong canine teeth (fang- like teeth seen in dogs), in the Other large-mouthed fishes front of their mouths for have weak teeth or none at all! grasping prey. Each species of Their mouths have other fish may have teeth located on structures that can hold prey, or different bones, or locations in strain out plankton. Some their mouths because of their whales, the largest sea specialized location in the creature known to man, have ocean. baleen. A baleen is a plate-like structure that is used to strain Pikes and many sharks have tons of krill and plankton from large mouths and many sharp the ocean water. teeth. Their appearance labels

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Fish have specialized mouths bite off chunks of coral. A for the way they feed, and what slipmouth is capable of they eat. Wolf eels feed upon extending their mouths to shelled animals, and have siphon prey. The thin snout- strong teeth in the front and like mouth of a butterflyfish is back for crushing its prey. The useful for removing food items two front teeth in parrotfishes from small cracks and are fused. This is so they can crevices. What are the Differences in Fish Fins?

The shape of fishes fins is unpaired fins are the dorsal, probably the most noticed caudal, and anal; the paired feature on the fish body. Fins fins are called pectorals and are composed of two groups, pelvics, or ventrals. unpaired and paired. The Paired Fins

Pectoral fins are present in The pelvic fins are generally almost every fish. They are smaller than the pectorals, and found behind the gill cavity, and more restricted in function. The are prominent. In primitive pelvic fins are located behind fishes, the pectoral fins are the pectorals. Pelvic fins found lower on the body, nearer function in stabilizing and the ventral side. In some braking, they are of little use for cases, these fins look like an locomotion. Some have spines arm-like extension. In other and rays on them. Other fish cases, the pectoral fins have have modified pelvic fins in the evolved to look like wings for form of a sucker, or use them the South American flying fish as an appendage to create and a pad for resting on the friction between themselves bottom in some catfish. Other and the substrate to help them fish have developed stay in place. Some fish have specialization in their fins for even lost their pelvic fins certain habits like protection, completely, especially those tactile organs, taste, and that spend their lives scouring crawling. along the ocean floor!

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Unpaired Fins

The dorsal fins have been modified dorsal in the remoras into a sucking fin, the disc that allows them to cling to caudal sharks or other large fishes. In or the the anglerfish, the dorsal fin tail fin, has been modified into a fishing and the rod and lure. Other fish have anal small finlets that have evolved fin are all unpaired fins. The from the dorsal ray. dorsal fin extends along the length of the back, the anal fin The anal fin is usually short, but is located on the ventral side of some fish have anals that the fish, and behind the anal stretch from near the chin, to opening, and the caudal fin is the caudal fin. Very few fish the tail. have more than one anal fin (i.e., the cods), and some do The dorsal fin may extend the not have one at all (i.e., skates entire length of the back, may and rays). In some species, be a fleshy ray, or quite large the anal fin has modified into an and supported by spines. organ used in copulation called Some fish do have 2 dorsal a gonopodium. fins,but they are not symmetrical and not considered The caudal fin, or tail fin, paired fins. The dorsal fin is appears in a variety of shapes, useful in stabilizing the fish as it sizes, and kinds. The shape of swims, helping to change the caudal fin might deduce direction quickly, or used with swimming habits. See the table the other fins for braking. The below.

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Diagram 4-1. Fish Tail Shapes Shape Name How they swim Where they live

Lunate Fast, rapid Pelagic (crescent)

Constantly Forked Pelagic moving

Strong Truncate swimmer, Pelagic slower Strong Rounded swimmer, Pelagic slower

Usually Leptocercal Wriggling bottom (long, whip-like) weak swimmer, ribbon-like Plankton, Leptocephalii body, wriggling pelagic motion

Weak swimmer, Pelagic or Small or or wriggling on bottom continuous with bottom body

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How Big is a Fish Mouth?

The mouth tells much about the mouth, and makes it easy to habits of a fish by its position, scoop fish and invertebrates shape, and size. The typical from the ocean floor. fish has a mouth at, or very near, the front end of the head. Some fish have a mouth that is Fish mouths have developed to sword-shaped. The top jaw of adjust to specialized lifestyles. the mouth has evolved into the The size of fish mouths can shape of a long sword that give a clue to its feeding habits, protrudes from the front of the especially when considered fish. Other fish have beak- with the type and placement of shaped mouths. The triggerfish teeth. has a beak-like mouth. Having a Bottom–feeding fishes have downward-pointing (subterminal) mouths, while

mouth this shape makes it easy for the fish to break off small surface oriented fish have pieces of coral. upward-pointing mouths (superior). Other fishes that The size of the mouth is usually catch their food directly in front directly related to the size of the of them as they are swimming prey, as is its shape. through the water have a Therefore, a fish that feeds on terminal mouth. Fish that are small invertebrates by suction flat, like the ray and feed have a small mouth surrounded directly off the ocean floor have by protractile “lips” that when a mouth on their belly, or protruded form an O-shaped ventral side. This kind of a opening. mouth is called an inferior

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What do Fish Eyes Look Like?

What do you think it is like to that they can see forward or live, and see underwater? backward, and up and down. Remember that calm water can (Wouldn't it be great if humans reflect up to 80% of the sunlight could see behind them, without coming in, and seeing through turning around?!) water is completely different The size of the eyes, relative to than seeing in air. Various the size of the fish, varies both species of fish can cope with according to the methods used life only at the bright surface, in to capture food and according brilliant coral reefs, dimly lit caves, dim bogs, or sheltered forest streams. Some even peer above the waters surface! As you can to the light levels under which see, all fish eyes are not the the food is taken. Well- same. Read on, and we will developed eyes are found in discuss a few differences. most fishes that are diurnal predators, although the largest The eyes of most fish are eyes are found in fish that feed placed on the sides of the at dawn and dusk. head. Fish do not have eyelids, with the exception of a few The night-active, or deep-water which have a nictitating eyelid. fishes that depend on other Most fish need to have a senses to find food, have maximum field of view, so their relatively small eyes, or none at eyes are spherical, with a all. Other fish have barrel-like bulging shape. Saltwater fishes or tubular eyes; while others have the ability to move their have fixed, four eyes, or aerial eyes better than fresh water vision as well as underwater fishes. Most fish have the vision. ability to move their eyes so

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Finally, some fish that have sensitive to light. These vary in poor eyesight, or are blind, fish, and help the fish to adapt have other organs that are to its environment.

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Activity 4-1. Fish Ecology Word Art

Objective: Students will draw on the information and vocabulary that they have learned to be illustrative and create an environmental or fish drawing. They will have and understanding of the vocabulary and concepts that are drawn from fish ecology, while at the same time, working on their spelling abilities.

Materials: Drawing utensils Paper

Procedure: 1. As a class list as many words as possible that will describe fish, the environment in which they live or recreation that surrounds fish ecology. • Use adverbs, adjectives, nouns, and verbs. Try to conjure up all possible words that describe how a fish survives, the environment(s) in which they survive, when a fish might swim upstream, etc. 2. While the students are coming up with these words, take the time to discuss the definitions of each word so that each student gains comprehension of the vocabulary. 3. Have each student copy down the list of words. 4. Finally, have the students use the words to ‘draw’ a fish or environment. They can mix words with lines, and other shapes. See Example:

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Activity 4-2. Mathematical Fish Find

Objective: Polish students’ basic mathematical skills through solving simple mathematical equations. After the equations are solved, the students will color by number to ‘find’ the hidden fish.

Directions: On the following page is a picture of several fish encoded in mathematical equations. Solve and then color according to the following. 1. Color all number 4’s orange. 2. Color all number 8’s green. 3. Color all number 7’s yellow.

Materials: Worksheet Coloring materials Mathematic skills

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1+1= 5*5= 7*7= 9*9= 4*9= 21/3= 9*2=

1*7= 56/8= 4+ 42/6= 2*3= 3=

24/6= 8*6=

8*7= 100/ 9+9= 1*5= 6*3= 10/10= 25=

8- 4= 72/8= 5* 1*4= 44/11= 2= 24/3= 36/6= 4+4= 2+2= 2*4= 1*8= 6*5= 3+ 2* 49/7= 12/6= 3= 10 2*12= 5*5= 4*5=

Student Information Sheet 4. Fangs, Fins, Mouths, and Eyes

By observing the features of a fish, a lot can be learned. Just by looking at the fangs, fins, mouths and eyes, information such as where the fish lives, how it eats and how it swims can be learned.

Shape Name How they swim Where they live

Lunate (crescent) Fast, rapid Pelagic

Forked Constantly moving Pelagic

Strong swimmer, Truncate Pelagic slower

Strong swimmer, Rounded Pelagic slower

Leptocercal (long, Wriggling Usually bottom whip-like) weak swimmer, ribbon-like Plankton, Leptocephalii body, wriggling pelagic motion

Small or Weak swimmer, or continuous with wriggling on Pelagic or bottom body bottom

The fins of a fish are also very evolved into an apparatus much interesting to look more useful to that particular fish. at. Most fish Look at the anglerfish, the dorsal fin have a pair of fins has become a fishing line and lure on their ventral used to catch prey. In the remora, side (belly), called the pectoral fins. These are often used for steering, quickly changing direction and braking. The fins that are observed on the dorsal side (top) of the fish the dorsal fin has become a sucker- are called the dorsal fins. The like apparatus so that the fish may caudal and the anal fins are located attach to larger fish without harming on the ventral side. If each of these it, and feed off its scraps. The tail fins is present, they are NOT found fins of fish all look very different as in pairs. In some fish, the dorsal fin well. It is easy to decide how a fish might extend the entire length of the swims by merely looking at the back, or the dorsal fin might have shape of the tail.

Fish Eyes: How different they all are!!

This fish looks forward, and swims through the water column. The food that it eats is caught in front of it. Since the fish is so flat, it also may have the ability to forage on the ocean bottom.

This fish is called a stargazer because of its upward, tubular eyes. The fish is a bottom dweller, but feeds well on the fish that swim above it.

This fish is a large mouth bass. The eyes on it are on the sides of the head, and can easily pick up on movement in the water. It feeds on fish as it swims through the water column, and can see all around its body; front, back, upward, and downward.

This is the jaw of the wolf eel. It Fish mouths and has strong canine teeth Functions used to bite shelled invertebrates. This is a protruding The subterminal mouth, good mouth. This is a fish for reaching called a dace. for small animals. This is a The thin mouth on the terminal butterflyfish is good for mouth, in getting small the trout. invertebrates from cracks Usually full and crevices. of sharp teeth. This is a tang, which The superior mouth, in has two front ladyfish, tarpon, and teeth fused herring is used to to form a capture food above it. beak-like mouth. The inferior A small terminal mouth in mouth in permit. sturgeons. Used for catching Good for food in front of it, upsetting food during swimming. lying in the benthos.