All About Arthropods

Arthropod Dissection Pre-AP Biology Period 2 - Bowen Song

Arthropoda

An arthropod is an animal having an exoskeleton, a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda. This word is derived from the Greek arthron, meaning joint, and the Greek pous, meaning foot.

Arthropods account for over 80% of all known living animal species and are found almost everywhere. They are important memebers of marine, freshwater, land and air ecosystems.

The phylum Arthropoda includes insects, arachnids, and crustaceans, but for the purposes of today's lesson, we will be focusing on the insect (grasshopper) and the crustaceans (crayfish).

Objectives

Students will learn about the internal and external anatomy of the phylum Arthropoda. They will focus on the organs, structures, and functions of the integumentary system. Students will also focus on the ecological presence of organisms in the phylum Arthropoda as well as the human influence on the phylum Arthropoda. Finally, students will learn the evolutionary characteristics of arthropods.

Grasshopper Internal and External Anatomy

Crustacean Internal and External Anatomy

Getting More in Depth

Parts of the Arthropoda integumentary system: pore canal filaments, opening of duct of dermal gland, seta, epicuticle, cuticle, basement membrane, tormogen cell, trichogen cell, dermal gland, epidermis, endocuticle, exocuticle

Functions: Arthropod exoskeletons are made of cuticle, a non-cellular material secreted by the epidermis, that serves as protection for the organism. Their cuticles vary in the details of their structure, but generally consist of three main layers: the epicuticle, a thin outer waxy coat that moisture-proofs the other layers and gives them some protection; the exocuticle, which consists of chitin and chemically hardened proteins; and the endocuticle, which consists of chitin and unhardened proteins. The exocuticle and endocuticle together are known as the procuticle. Each body segment and limb section is encased in hardened cuticle. Unfortunately, the exoskeleton cannot grow and expand as the organism grows and expands and so as a result of this conundrum, arthropods molt and shed their exoskeleton when they are too big for it.

Another function of the arthropod integumentary system is for the senses. Arthropods have modified their cuticles into many different kinds of sensors. Various touch sensors, mostly setae, respond to different levels of force, from strong contact to very weak air currents. Chemical sensors provide equivalents of taste and smell, often by means of setae. The arthropod integumentary system is magnificent indeed.

Ecological Presence

The organisms in the phylum Arthropoda can be found nearly everywhere and account for a vast majority of all known living species. Arthropods serve as both predator and prey in the food chain. They are hardy creatures that have adapted and grown to match their own certain circumstances. The crayfish getting adapted to water habitats and the grasshopper getting more fit to live in green areas are excellent examples of this adaptation happening in nature. Countless other species of Arthropoda are similarly adapted and just as hardy.

Evolutionary Characteristics

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