✪ Arthropod "Dissection" ✪

~Emily Sanchez~ Vu PAP Bio p.2~

✪ Objective ✪

The student will learn about the interesting integumentary system of an Arthropod and observe the similarities between different Arthropods and their exoskeletons, etc.

✪ Background Information ✪

Scientific Name: Arthropoda (phylum)

Habitat: Everywhere in the world. Arthropoda is a phylum with a wide range of animals that compose it. They can live from the bottom of the ocean to the sands of a hot desert or in the beach.

(From now on, the focus will be on crayfish)

Scientific Name: Cambarus (genus)

Predators: raccoons, opossums, snakes, and muskrats.

Prey: aquatic plants, mollusks, insect larvae, mature insects, tadpoles, amphibian eggs, and small fish are common foods.

Niche: The fundamental niche is that is an omnivoric scavenger

Trophic Level: 2- primary consumer and 3- secondary consumer.

Adaptations: breathing through gills under the carapace, eyes are on

movable stalks to allow sight in different directions, ability to emit chemical

cues to identify one another and signal mating, and can even change color to match their habitat.

✪ Dissection (Observations and Comparing) ✪

✪ Integumentary System ✪

The bodies of arthropods are covered by an exoskeleton, or cuticle, that contains chitin. This makes up the integumentary system. The tough outer covering, against which muscles work, is secreted by the epidermis fused with it. The exoskeleton remains fairly flexible at specific points, allowing the exoskeleton to bend and appendages to move. The exoskeleton protects arthropods from water loss and helps to protect them from parasites, predators, and harm.

The exoskeleton does not go through growth, but molts. For a crayfish to grow, it must shed its exoskeleton and then re-grow a new and larger one. When a crayfish moults it is very vulnerable to both injury and predation so, they must spend the two or three days it takes to re-grow its exoskeleton relatively inactive in its refugia. Young crayfish molt 6 to 10 times during their first year while older crayfish moult 3 to 5 times during their second (and, typically, final) year of life.

✪ Info From Inside the Exoskeleton ✪

  • Living arthropods are divided into four subgroups: Chelicerates (spiders, scorpions), Crustaceans (lobsters, crabs), Hexapods (most insects), and Myriapods (millipedes, centipedes)
  • Ancestral arthropods were the first land animals.
  • Arthropods employ a variety of reproductive methods.
  • When arthropods grow, they must molt their exoskeleton.
  • Arthropods comprise over 90% of the animal kingdom.