Grasshopper or Crayfish?

Doesn't matter, they're both Anthropods!

Zainab Jimoh - Vu PAP Bio 3

Objective

In the Arthropod lab, you will....

  • examine two preserved anthropoid - a grasshopper and a crayfish
  • look for similarities in the grasshopper and crayfish that will show they belong to the same phylum
  • look for differences in the grasshopper and crayfish to show that they belong to different classes.

The Crayfish

Class Crustacea

Crayfish, also called crawfish or crawdad have more than half of the 500+ species located in North America, particularly Kentucky (Mammoth Cave) and Louisiana in the Mississippi basin. Crayfish also live in Europe, New Zealand, East Asia and throughout the world, including the Tristan da Cunha Islands.

Crayfish are Crustaceans, and are closely related to lobsters, crabs, and shrimp. Crayfish are characterised by a joined head and thorax, or midsection, and a segmented body, which is sandy yellow, green, or dark brown in colour. The head has a sharp snout, and the eyes are on movable stalks. Crayfish are usually about 7.5 cm (3 inches) long.

Taxonomy

Kingdom: Animalia

Phylum: Anthropod

Class: Crustacea

Order: Decapoda

Family: Cambaridae

Genus: Cambarus

Species: bartonii

Niche

The crayfish’s niche is that it's an omnivoric scavenger that likes to eat aquatic plants and small invertabrates, like insects, and is eaten by many other animals, like raccoons and bass. It also has a large geographic range that includes both freshwater and saltwater habitats.

Integumentary Sytstem

This crustacean has a hard exoskeleton that protects and supports the body. The crayfish has 8 jointed walking legs, a segmented body, 2 pairs of sensory antennae, and compound eyes. It has 2 large pincers or claws called chelipeds. If a crayfish loses a leg, the leg will regenerate (regrow). The head and thorax are fused, forming the cephalothorax. Using gills, a crayfish breathes oxygen that is dissolved in water. Juvenile crawfish are light tan, but adults are deep red.

The exoskeleton is composed of many layers. It is laminate, this makes it strong but flexible. The most important substance that the exoskeleton is composed of is chitin. Chitin is a protien composed of long molecules bound together in bundles that gives the exoskeleton the unique combination of strength and flexiblity. The exoskeleton acts as a barrier to damage and keeps out parasites and diseases. It also provides a waterproof layer to prevent waterloss. The exoskeleton of a crawfish is divided into a series of segments, each of which performs specialized functions. The cephalothorax, consisting of the head and thorax, bears all of the limbs used in sensory perception, locomotion, breathing, and the detection and capture of prey. The abdomen is divided into six segments that are responsible for rapid locomotion.

Human Impact

American crayfish species can be carriers of the so-called 'crayfish plague' - a disease caused by a fungus (Aphanomyces astaci). The 'plague' does the American crayfish little apparent harm but is lethal to European species such as the white-clawed crayfish. Crayfish plague carried by signal crayfish is one of the main reasons for the collapse and extinction of native white-clawed crayfish across Europe, including in Britain.
Some species of invasive crayfish can cause additional damage to river systems by constructing burrows in the banks leaving them prone to collapse. This presents a hazard to human health and safety by weakening walkways and of the river side and impacts on the flood defence of the areas affected.

Crayfish in Tanzania

Bookend Trust - Burrowing Crayfish

The Grasshopper

Class Insecta

Grasshoppers are complex insects and have many specifics when it comes to their body systems and functions. Grasshoppers, like all insects, have a three part body of a head, thorax, and abdomen. They also have compound eyes like other insects. However, their legs and wings set them apart from others because of the jumping legs as well as walking legs that they use and the layer of wings they use to fly. Their segmented bodies are made up of a hard exoskeleton of tagmata.

Taxonomy

Kingdom: Animalia

Phylum: Arthropoda

Class: Insecta

Order: orthoptera

Family: Acrididae

Taeniopoda varipennis

Ecology

Niche

Grasshoppers can be important herbivores. There are sometimes so many, eating so much, that they change the richness and abundance of plant species where they live.


Grasshoppers are also an important food for other animals. Some species eat weed plants that are bad for cattle and horses

The Respiratory System

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 air sacs that the tracheal system works to create can be compared to human alveoli because it stores carbon dioxide and oxygen when the respiration is taking place. However, we take air in from our mouths and nose while their spiracles do that with the control of their brains. A few of the spiracles are involved in the expiration of air as well. The human tracheae performs the role of cleaning air while the grasshoppers tracheal system works as an independent function not involving the circulatory system.

Learn More About the Grasshopper

Human Impact

Although grasshoppers are generally considered pests--and, in large numbers, can wreak wholesale destruction on crops--they're also useful to people. Grasshoppers serve as valuable subjects of scientific research, provide humans and other animals with food, help control weeds and contribute nutrients to the ecosystem.
Grasshoppers serve as a high-protein, nutrient-rich source of food for people in parts of Africa, Asia and the Middle East. When large numbers of grasshoppers decimate crops, humans can eat the grasshoppers to avoid starvation, but that's not the only time the insects serve as entrees. According to an exhibit at the Pacific Science Center in Seattle, Wash., grasshoppers are actually quite tasty.

Anatomy of the Grasshopper

Grasshopper Anatomy Part 1

Fun Facts

1. Grasshoppers and locusts are the same: when they emigrate in swarms they are called locusts.

2. A grasshopper’s eardrum is on its abdomen, so you could say they hear with their bellies.

3. The fossil record shows that grasshoppers have been around for 200 million years and had evolved before the dinosaurs appeared.

4. Grasshoppers are good at detecting rhythm, but bad at detecting differences in pitch of notes.

5. They make noises by stridulating (rubbing the hind leg against the wing) and crepitating (snapping the wing in flight).

6. The 10,000 or so different species of grasshopper have distinct identifying rhythms.

7. In Japan, grasshoppers are seen as a sign of good luck.

8. Grasshoppers can jump a height of about 25cm and length of a metre.

9. A small cuticle in a grasshopper’s knee acts as a spring and lets it catapult its body into the air.

10. Eating insects is called ‘entomophagy’. Chapulines fundido (grasshopper fondue) consists of crispy fried grasshoppers on a bed of a puree of grasshoppers with shallots, garlic and chilli.