Grasshoppers hatch from eggs looking like tiny grasshoppers. They undergo incomplete metamorphosis, meaning each molt adds a few more adult characteristics. Most grasshoppers molt five to six times before maturity. Grasshopper wings appear with the final molt. While eggs may overwinter, grasshoppers usually die when the weather turns cold. In warmer climates, predators, drought and disease control grasshopper populations.
Crayfish belong to the subphylum Crustacea. Most crustaceans live in the ocean, but the crayfish habitat is freshwater. Although freshwater crustaceans generally are called crayfish, different regions may argue that the name is crawfish or crawdads.
Crayfish are omnivores. Young crayfish eat 1 to 4 percent of their body weight every day and feed primarily on animals. Mature crayfish consume between 0. External crayfish anatomy exhibits a chitinous exoskeleton with two body segments, a cephalothorax and an abdomen. Attached to the cephalothorax are four pairs of walking legs and a front pair of legs modified with large claws. Crayfish have two pairs of antennae. Crayfish breathe using gills. If their aquatic environment dries up, however, they can estivate a type of hibernation in burrows or walk across land to find water.
Crayfish mate in early spring. The developing eggs remain inside the female crayfish for four to six weeks. The female then attaches the eggs to her tail using a special glue called glair. Only 20 to 40 percent of the eggs will hatch in late spring.
Crayfish molt six to 10 times during their first year of life but only three to five times during their second year. Most crayfish live about two years. As members of Phylum Arthropoda, grasshoppers and crayfish share many characteristics. They both have a hard chitinous exoskeleton with jointed legs, segmented body, compound eyes, digestive system in a body cavity, nervous system and open circulatory systems. Both grasshoppers and crayfish exhibit two genders.
They both reproduce with eggs and must molt to grow. How do the various groups use their legs to walk, swim, feed or mate? Watch the way the millipede moves. Look at the legs. See how the waves of muscle contraction pass down through the segments? The polychaete worm Nereis moves in exactly the same way.
Handle the millipedes very gently. They are someone's pets. They also make great pets for dorm rooms - they need little care, don't take up much room, and don't make noise or messes, unlike your roommate.
Disturb the centipedes to get them moving around. Can you see the poison fangs? Notice how flat the body is, and contrast the number of legs with those of the millipede. Why does each container hold only a single centipede? Don't open the jars unless you have a thing for extreme pain. Play around with the roly-polys. Oh, go ahead, it's cool. They won't bite. Watch the way they roll up into a ball when disturbed. Not all isopods can do this, but rolling up into an armored ball is a great defensive tactic.
Compare our teeny tiny terrestrial version with the enormous preserved marine isopods. Look at the live brine shrimp, hermit crabs and fiddler crabs. Treat them gently more pets. Watch the way they use their legs, including the modified legs that form their mouthparts. You may see the male fiddler crabs raise their large claw and wave it about to claim a territory inside the tank, in the hopes of attracting a mate Can you blame them? Observe the live crayfish. What does the crayfish do when it feels threatened?
How does it use its swimmerets when it is stationary? Observe the diversity in insect mouthparts etc. Don't worry about being able to identify the individual slides.
Try to get a feel for the way modified legs are employed in these animals for a wide variety of sucking, sponging, piercing and biting. Observe the insects on display. You should be familiar for lab and lecture with the common orders of insects listed in this guide. Crayfish are relatively easy to dissect. Many of you have had ample practice dissecting them at Jazz Fest. Your first task is to determine whether you have a male or female crayfish. Turn the animal on its back, and examine the area of the thorax where the legs join the body.
Female crayfish have a circular opening, like a tiny doughnut, which is their seminal receptacle. Male crayfish have a hardened pair of swimmerets legs on the abdomen that extends back towards the head, and fits neatly into the groove between the walking legs. These modified legs are stiff, like hard plastic. They are curved like half a soda straw, and when they are joined together, they make a tiny tube through which the sperm travel during copulation. Crayfish literally copulate with their legs.
Observe their external anatomy. Identify the following structures: rostrum, antennae, eyes, thorax, carapace, chelae claws , cheliped, walking legs, abdomen, swimmerets, telson, and uropod. Examine the various appendages and modified appendages closely. Note that some are biramous ex. The uniramous appendages result from the evolutionary loss of the second branch. Note that each pair of antennae are biramous appendages. Examine the telson and uropod. How does the crayfish use these biramous appendages to escape predators?
Using a probe, try to find the mouth and anus. Note the thick triangular mandibles , a primary trait of crustaceans. Place the crayfish in the pan with its dorsal side up. Carefully cut the carapace just to one side of the midline with your scissors, and down along both sides. Peel it back to expose the gills. Notice how the gills interface with the legs, and observe the second underlying row of gills.
Cut away the gills where they join the body. Try to find the tiny heart good luck! Just under the heart are the gonads ovaries or testes. Look for the esophagus and stomach you can always insert a probe through the mouth to see where it emerges.
Carefully remove the internal organs, and look for the tiny brain near the base of the antennae. Ecologically, they are critically important herbivores. Arthropods are the primary converters of plant tissue to animal tissue on the planet! Trilobites were among the most successful arthropods on Earth, once numbering over 10, species.
Why are they all gone? Arthropods are the most successful animal phylum in terms of species diversity, distribution, and sheer numbers coelomate body segmentation modified metamerism hard exoskel jointed appendages.
Limulus- horseshoe crab Argiope- garden spider. Both contain one pair of chelicerae, one pair of pedipalps. Cabarus- crayfish. Cabarus- crayfish found where? Romalea- grasshoper. Romalea- grasshoper found?
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