An Arthropod Affair

Sam Golden- Arthropod Disection- 4/7/14 - Vu PAP Bio 4th

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-Arthropods (Arthropoda) are a group of invertebrate animals that includes centipedes, millipedes, spiders, mites, horseshoe crabs, scorpions, insects and crustaceans. There are more than one million known arthropods species and many millions more that have yet to be named. Scientists estimate there may be as many as 30 million species of arthopods (most of which are insects). Arthropods are a highly successful group of animals. They evolved more than 500 million years ago and are still going strong. They have colonized a vast variety of ecological niches around the globe and have evolved into a multitude of forms.

-Arthropods are classified under kingdom Anamalia, and have 5 subphylums: Trilobitomorpha, Chelicerata, Myriapoda, Crustacea, and Hexapoda.

-All arthropods have a segmented body, an exoskeleton, and jointed appendages

-The term "arthropod" comes from the Neo-Latin and Greek "arthon" (joint) and "podus" (footed) in the 18th and 19th century.

-All arthropods have a segmented body, an exoskeleton, and jointed appendages


-To explore the environment, life, and role of arthropods (crayfish and grasshoppers).

-To analyze the anatomy of arthropods (crayfish and grasshoppers).

Arthropods and Humans

While some arthropods become agricultural pests, others help keep weed populations in check. Other arthropods consume the pests that see your vegetable garden as an all-you-can-eat buffet.

In addition to this, many arthropods can be a food source for humans.

Focus Animal 1: Grasshopper

Focus Animal 2: Crayfish

The Dissections

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System at a Glance: Respiratory

Aquatic arthropods (crustaceans) have gills for respiration. Gills are always outgrowths of the skin and are therefore covered by the exoskeleton, which is thin in this area and not a barrier to the exchange of gases.

Terrestrial arthropods possess tracheae and book lungs as respiratory organs. Tracheae are a system of tiny tubes that permit passage of gases into the interior of the body. In some arthropods the tracheal tubes are bathed by blood, but in insects the minute terminal endings (tracheoles) are embedded in the tissues, even within muscle cells. The tracheal tubes (but not the tracheoles) are molted along with the rest of the exoskeleton. Tracheal systems are highly efficient for the small, terrestrial animals. The small, external openings (spiracles) reduce water loss, the chitinous lining prevents collapse, and the small size of the arthropod and consequent short length of the tubule eliminates the need for moving gases in and out by active ventilation.

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