Arthropod Lab By:Mariam Moini, Mitcham P2


Look for the similarities in the crayfish and grasshopper that may be phylum traits.Be able to identify the differences between the two animals that may be class traits.Take a closer look at the repsiratory system of the grasshopper and crayfish.

About Arthropods

There are four major types of arthropod. Three are found around you while one group is extinct. Trilobites are an extinct group that can be found in fossils around the world. Chelicerates include species such as spiders and horseshoe crabs.Uniramians include centipedes, millipedes and the biggest group of arthropods. Insects. Crustaceans are the last category of arthropod. Crustaceans include crabs and lobsters. They are mainly aquatic species. All arthropods have; a segmented body, an exoskeleton, jointed appendages,bilateral symmetry and numerous pairs of limbs

Background Information of Crayfish

Scientific Name

Astacoidea is the scientific name of crayfish.


  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Crustacea
  • Class: Malacostraca
  • Order: Decapoda


Crayfish are omnivorous. Crayfish eat fish, shrimp, water plants, worms, insects, snails, plankton, and more. They are scavengers and will eat dead things, as long as they are relatively fresh.Crayfish are consumed by animals such as raccoons,opossums,muskrats, and snakes.


There are over three hundred kinds of crayfish present in North America. Each crayfish lives in a specific habitat, but considering the large amount of species, they can be found in most aquatic and semi-aquatic environments throughout Canada and the United States.Crayfish can be found in about any body of water that isn't over polluted.

Fun Facts

  • Crayfish will create a home for themselves under a rock or a bank by moving smaller items around. They are aggressive and defend their territories.
  • Crayfish are Crustaceans, and are closely related to lobsters, crabs, and shrimp
  • They have ten legs; the front two have developed large claws called "Chellae."
  • There is a species that is blue. It is called a Blue Crayfish. There are also red and white crayfish.
  • The red crayfish is the most common, the blue is the second most common, and the white crayfish is the least common.
  • The most common crayfish gets 3-4 inches long, but they can get much bigger in the wild in deep lakes.
  • Adult size is reached by crayfish in the wild in about 4 years. They can live from 20 to 30 years.
  • Crayfish have adapted their eyes, pincers, reproduction methods and color over time.

THE RESPIRTORY System of Crayfish

The crayfish has the advantage of being able to breathe underwater because of their gills.The crayfish's gills are located on the outside of the body between the crayfish's body wall and carapace. The crayfishes gills are attached to the walking legs, so when the crayfish walks the gills spread out giving space for oxygen to enter. As the crayfish walks, it can breathe at the same time.
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Relationship to Humans

Many people eat crayfish. They are also used by fisherman as bait.

Crayfish help humans in other ways, such as cleaning up dead animal and plant matter from the bottom of streams, and by controlling populations of insects and other animals.

Background Information of Grasshoppers

Scientific Name

"Caelifera" is the scientific name of grasshoppers.


Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Hexapoda

Class: Insecta

Order: Orthoptera


The prey of a grasshopper are: crops,and plants.They will eat almost any type of leaves, but they prefer soft vegetation. The predators of a grasshopper are: rodents, especially mice, Insects like the mantis, spiders, birds like seagulls and reptiles. Frogs also eat grasshoppers.


The northern grasshopper has a wide variety of habitats,mainly in regions of North America, including mountain meadows, bogs and swamps, and arctic tundra.

Fun Facts

  • They have no ears, but they do hear with an organ called tympanum.
  • When grasshoppers are picked up, they “spit” a brown liquid commonly called “tobacco juice.” Scientists believe this liquid may protect them from attacks by predators.
  • Males sing, by rubbing their back legs against their wings, to attract females and to warn off other males

RESPIRATORY System of a Grasshopper

The exchange of gases in a grasshopper happen through the tracheal system but begins at the spiracles where air is taken in first.This system contains of ten spiracles located in the abdominal area and the others are thoracic. Oxygen diffuses into cells directly into the atmosphere and that completes the grasshoppers process of respiration.The grasshoppers tracheal system works as an independent function not involving the circulatory system.

Spiracles-small holes where tracheae open to the outside (you can see those as little dots on the abdomen of a grasshopper)

The spiracles are guarded by

  1. valves controlled by muscles that enables the grasshopper to open and close them;
  2. Hairs that filter out dust as the air enters the spiracles.

Tracheae- a system of air-filled tubes where oxygen and carbon dioxide are exchanged between tissues

Air Sacs- the area where the oxygen flows to once inside the spiracles, these are temporary storage spaces for air as the oxygen is passed through the body

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Grasshoppers Relationship to the Surrounding World

  • Grasshoppers benefit ecosystems through their droppings,which contain plant nutrients that enrich the soil and fertilize new plant growth.
  • Grasshoppers also serve as food for other insects, birds and small mammals.
  • Grasshoppers serve as a high-protein, nutrient-rich source of food for people in parts of Africa, Asia and the Middle East.
  • Scientists use grasshoppers to study how various chemicals would impact humans and as test subjects for new drugs.
(Bos, Monique. "How Are Grasshoppers Useful to Humans?" EHow. Demand Media, 16 Apr. 2010. Web. 07 Apr. 2014)