Oxbow Virtual Lesson Something’s Fishy

Overview

This Oxbow Virtual Lesson is designed to introduce students to the different adaptations of fish.

Outline:

1. Fish facts
2. What is a fish
3. Fish adaptations
4. Types of fish
5. Build a Fish

Standards

Third Grade:

• S3L1. Obtain, evaluate, and communicate information about the similarities and differences between plants, animals, and habitats found within geographic regions (Blue Ridge Mountains, Piedmont, Coastal Plains, Valley and Ridge, and Appalachian Plateau) of Georgia.
  • b. Construct an explanation of how external features and adaptations (camouflage, hibernation, migration, mimicry) of animals allow them to survive in their habitat.
  • c. Use evidence to construct an explanation of why some organisms can thrive in one habitat and not in another.

Fourth Grade:

• S4L1. Obtain, evaluate, and communicate information about the roles of organisms and the flow of energy within an ecosystem.
  • c. Design a scenario to demonstrate the effect of a change on an ecosystem. (Clarification statement: Include living and non-living factors in the scenario.)

Fifth Grade:

• S5L1. Obtain, evaluate, and communicate information to group organisms using scientific classification procedures.
  • a. Develop a model that illustrates how animals are sorted into groups (vertebrate and invertebrate) and how vertebrates are sorted into groups (fish, amphibian, reptile, bird, and mammal) using data from multiple sources.

Aquatic – though some fish can spend time out of the water, all fish must return to the water in order to breathe and keep from drying out.

Gills – fish have permanent gills (unlike macro invertebrates) most also have fins, scales or skin, a slimy mucus, and a swim bladder

Fins – are thin membranes usually supported by rays or sharp boney spikes

Vertebrates – fish are one of the 5 vertebrates in the animal kingdom. They are however the only one that is able to live in the water without breathing air from the atmosphere.

1. Fins

Fins – are thin membranes usually supported by rays or sharp boney spikes:

• Dorsal – helps keep it upright
• Anal – helps it move in tight places and keep balance
• Adipose – some fish like salmon, trout, and catfish have this fleshy fin on their backs behind the dorsal fin
• Pectoral – helps it to remain in one place and to dive or swim to the surface
• Pelvic – helps the fish to stay in position and keep balanced
• Caudal –  helps it to move and largely determines a fishes speed and maneuverability

2. Scales

Scales – are found on some fish but not others like a catfish.

Fish do not grow more scales as they get older, the scales just grow bigger.

As the fish grow, each scale grows rings like the cross-section of a tree.

Scientists can use this to tell the age of a fish.

3. Gills

Gill cover or Operculum and gills – most fish breath by alternately opening its mouth to let in water, and then shutting its mouth and forcing the water back over its gill openings.

As the water passes over the gill filaments, dissolved oxygen is exchanged for carbon dioxide. Mention that some fish do not breathe this way.

Lungfish and coelacanths, which were thought to be extinct until 1938, breathe using a lung.

4. Swim Bladder

Swim Bladder  – some fish contain a swim bladder with allows them to suspends themselves in water and not sink to the bottom.

In most fish it is an air-tight sac, while in other fish can add or release gas to remain in either deep or shallow water.

Fish like mackerel, sharks and tuna do not have a swim bladder and must stay in constant motion to keep from sinking to the bottom.

5. Mucus

Mucus – helps to protect fish from disease, fungi, and parasites.

It reduces friction in the water making it easier for the fish to swim.

Vision

Most fish have an almost 300 degree field of vision. One of their main “blind spots” is the spot behind their tails, the other is the tip of their nose. Most fish will face upstream in a current and so many fishermen fish streams by wading upstream. These fish have binocular vision – they can see three dimensions (height, length, and depth) of about 30 degrees to the front and directly above their snouts. Other than those 30 degrees fish can only see how tall or wide and object is. Fish are often nearsighted. Scientists believe that freshwater fish have good color vision, especially those in shallow water habitats. Many fish are nocturnal and have far more rods then humans do. This is also true some fish that live in deeper water and need more rods in order to find their prey.

Smell

Fish use there sense of smell to locate food, or find a mate, while migratory fish use it to find their way home (example Salmon can detect smells from where they were born from hundreds of miles away). The smell, or olfactory sense, is located in the nostrils. There are two pairs of nostrils called nares on both sides of the fish’s snout. Water flows through the nares as the fish swims, by current, or pumped through as the fish breathes. Fish have a very sensitive sense of smell.

Taste

Fish have taste buds found on their lips, in their mouth, and deep inside the mouth. Humans have about 10,000 taste buds, yet fish have even more. The taste buds react to chemicals dissolved in the water. Catfish even have taste buds on their skin and barbells, and can taste things from 15 feet away.

Hearing

A fish’s sense of hearing must count on two different organs working together to locate and sense sound around them. One is its lateral line working together with its inner ear. Ask the students if they can remember how the lateral line works. The inner ear is located on both sides of the brain.

1. Jawless Fish

Jawless fish (agnatha) – lack jaws, paired fins and do not have scales. Instead they have skin.  They have a cartilaginous skeleton.

Some examples of this are hagfish, and lampreys.

The Least Brook Lamprey is native to parts of the Southeast.  Though some species are not parasitic, many are.  The sea lamprey gets its food by clamping its mouth onto the side of an unsuspecting fish.  It then uses its rasping tongue to make a wound and then sucks the blood out of its prey.

There are around 63 species of jawless fish.

2. Cartilaginous Fish

Cartilaginous fish (chondrichthyes) – have a skeletal structure made of cartilage.

These fish may have either skin or scales. If they have scales they with usually be diamond shaped and some will even have barbs on them. Examples of these fish are sharks, rays and skates. In the Southeast, some examples are the southern stingray, smalltooth sawfish, and various sharks.

A cartilaginous fish is denser than the water around it, so it must stay in almost constant motion or rest on the bottom.

There are approximately 850 species of this fish.

3. Boney Fish

Boney fish (osteichthyes) – have skeletons made of bone.

This superclass makes up 95% of all fish and about 40% of these are freshwater fish.  The class can be further divided by lungfish and ray-finned fish.  They have either skin or scales with are usually thin and overlapping.

Examples of these are bass, catfish, salmon, and pike.

There are over 18,000 species of this fish on earth.

1. Camouflage

Camouflage is very important to many fish.

Often a fish that is found mainly in the weeds will have vertical bars or stripes on its body.

Open water fish may have stripes or counter-shading where the belly of the fish is lighter than that of its back.

2. Shape

The shape of a fish is often determined by its habitat.

A catfish is flatter and bulkier and spends most of it’s time on the bottoms of lakes and streams.

A hogchoker, a fish found in the gulf and estuaries of Alabama is a small, right eyed flatfish.  It begins its life upright, but as it ages the fish gradually becomes flattened and its left eye moves on top as the fish’s habitat becomes more the bottom of the water.

3. Mouth

The mouth is often an indicator of what a fish eats.

A grouper has large jaws indicating its prey is quite big.

A barracuda is well known for its teeth and fact that it is a carnivore.

A cod has an elongated upper jaw and a single whisker, called a barbell, with is on it’s downturned mouth. Both of these are indicators that it can find food on the bottom of its environment.

4. Speed

The speed at which a fish moves helps it to survive.

Normally, fish swim about as fast as a human can walk, however some fish like a bass or trout have been clocked at over 20 mph.

5. Defense

Some fish have many different forms of defense.

An example of this is in the Southern stingray, found off the shores of Georgia, which, though it will not attack, if stepped on or provoked has spines that are poisonous.

Catfish are also sometimes known to “sting” and the term “finned” is reference to a fish using it’s fins as a defense against an unsuspecting fisherman