Respiratory system of Arthropods

Crayfish and Grasshopper-PAP Bio- 3/14/14- Xiong, Lizi

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Chorthippus brunneus

The grasshopper belongs in the suborder Caelifera in the order Orthoptera. Grasshoppers are characterized by short antennae and short ovipositors. They have mandibles to tear off food with. They announce their presence by snapping their wings in flight or rubbing their hind femurs against their abdomen. Females have two valves in the back to dig for egg-laying.

Grasshoppers are often confused with crickets, but are actually very different. The ovipositors have different structures and the antennae have different lengths. The differences between the orders occurred about 252 million years ago, in the Permian–Triassic extinction event.

Today's Objectives

Students will be learning about the external and internal anatomy of a grasshopper. Students will focus on the organs, structures, and functions of the respiratory system. Students will also understand the ecological role of the grasshopper

Cladogram of Grasshopper

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Respiratory system at a glance

10 pairs of spiracles (8 abdominal, 2 thoracic) are located on the side of the body. Fine hairs on the spiracles prevent foreign objects from entering and interfering. Also, valves open and close in response to conditions. The atria are small spaces that the spiracles are connected to, that develop into air tubes called the tracheae. A wall of cells surrounds the tracheae. A single layer of epithelial cells secrete thickening material to give support. Oxygen is inhaled through the first 4 spiracles and the last 6 spiracles release carbon-dioxide.


Thoracic spiracles: allow oxygen and carbon dioxide exchange

Tracheae: air filled tubes which open through pairs of spiracles

Tracheoles: carry oxygen throughout the body


The respiratory system is maintained by the nervous system.

Taxonomy

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Human Impact

Some grasshoppers are eaten as a delicacy, especially in Africa, Asia, and the Middle East. Grasshoppers mate by rubbing their femurs against a front wing. However, human-created noise have caused grasshoppers to change their tune (the sound emit from different frequency levels). Grasshoppers are known to ravage entire harvests, consuming fields of food. Humans have tried to eradicate these pests with chemicals.
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Cambarus genus

Crayfish (also known as crawfish, crawdads) are in the order Decapoda.


They belong to the kingdom Animalia under the phylum Arthropoda and subphylum Crustacea. The adult is characterized by a jointed body with a sandy yellow, green, or brown color. The eyes are mobile stalks. The common name "crayfish" originates in France, where they were known as "écrevisses".

Crayfish do indeed look like mini lobsters. In fact, the lobster and the crayfish are closely related. They are both taxonimcally under the superfamilies Astacoidea and Parastacoidea.

Today's Objectives

Students will be learning about the external and internal anatomy of a crayfish. Students will focus on the organs, structures, and functions of the respiratory system. Students will also understand the ecological role of the crayfish.

Evolution of Crayfish

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Catching a crayfish by hand

Respiratory system at a glance

The Crayfish is unique because its gills are located outside the body. It is between the carapace, exoskeleton of the cephalothorax, and the lateral body wall, branchial chamber. They are attached to the walking legs so that the crayfish can walk and breathe. Every step taken will spread the gills, allowing water to be filtered. Also, crayfish have a water pouch to hold water. This is an advantage because crayfish are able to travel on land while breathing with their gills.


Gill: Filters water for oxygen

Carapace: Bony, chitinous shell; provides protection for gills

Water pouch: holds water so that crayfish has adequate air supply

Legs: Gills are attached to legs so that crayfish can breathe while walking


The respiratory system is closely linked to the nervous and muscular systems.

Basic Cladogram

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Human Impact

Crayfish are harvested for food. In the United States, crayfish production totaled $224,000 in exports in 2009. China provides $62.5 million in crayfish meat and the US provides $71.9 million in meat. Wild crayfish are also occasionally harvested if there is an abundance.

When Hurricane Katrina hit Louisiana in 2005, the US lost $743,000 from 2004. The crayfish industry was heavily impacted by the hurricane. In 2009, exports were up to $224,000.

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