The Amazing Arthropod Dissection

By: Michael Flora- Pap Bio- Mitcham- Period 2

Objectives

- To study the external anatomy of an Arthropod

- To understand what an Arthropod looks like

- Look for similarities between organisms of the same phylum

- Look for differences between organisms of the same phylum

Background Information

The scientific name of a grasshopper is Caelifera. Depending on the type of species of grasshopper will determine the other part to the scientific name. The scientifc name of a crayfish is Astacoidea. The habitat of an arthropod is numerous and varied from anything that is not under extreme conditions. There is a picture below to show the various habitats. The predators of grasshoppers and other arthropods are lizards, birds, rodents, and spiders. The prey are grasses since grasshoppers are herbivores. Arthropods are so diverse and so widespread that there is no one niche that is covered between all, so there is a large number of niches an arthropod can have depending on the ecosystem. Many adaptations include hard exoskeleton, segmented bodies, open circulatory system, and etc. The link below the picture is a link describing the evolutionary relationships between arthropods.

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Integumentary System

Arthropods are invertebrates that have an exoskeleton. The exoskeleton is their integumentary system. The skin is hard, and made up of a tough polymer called Chitin. It acts like an armor, and protects them against predators. It also prevents their bodies from drying up, which helps them to survive in extreme dry conditions like the desertsexoskeleton has four layers, namely epicuticle, procuticle, epidermis and basement membrane. The topmost layer, or the epicuticle, serves to lock in water, while the procuticle is the layer that gives strength to the exoskeleton. The third layer, or the epidermis, is responsible in secreting the procuticle. The muscles of the arthropods are attached to the exoskeleton. The exoskeleton is divided into head, thorax and abdomen. In spiders, their head and thorax are fused and is called Cephalothorax, as the exoskeleton is divided into cephalothorax and abdomen. The exoskeleton has one disadvantage. It does not grow with the rest of the body. So, it has to molt or shed its skin when it gets too small for the body. Before the shedding process, the cuticle separates from the epidermis in the process called as Apolysis. Then the epidermis secretes a new cuticle, which is soft and takes time to harden. Hardening occurs with dehydration of the cuticle. The new skin will be pale, and it darkens as it becomes harder. In this molting stage, the arthropod has to be careful as it is vulnerable to attacks from predators. Here is a picture below of the integumentary system.
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Functions Of Integumentary Organs

1. Exoskeleton: To protect inside organs

2. Head: Site of majority of sensory organs

3. Thorax: Body segment with wings and legs attached.

4. Abdomen: Part of body that contains reproductive and digestive organs.

5. Antennae: Detect smell,touch, and movement.

6. Legs: Enables movement

Extra Information

1. Grasshoppers can be as big as 5 inches long.

2. Grasshoppers go through 3 stages of development when being born.

3. Grasshoppers make sound by rubbing their wings or legs together.

4. 350 different species of crayfish live in the United States

5. 500 different species of crayfish live in the world.

6. There is a crayfish called dwarf crayfish that is very small.