Crustaceans Vs. Flightless Insects
Some of the more common types of crustaceans are lobsters, crabs, shrimps and barnacles; there are also terrestrial crustaceans such as the wood louse. The majority of insects have wings, but there are a few types that are wingless or have wings but never achieve flight: silverfish, water bugs and some beetles.
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Features
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Crustaceans and flightless insects share many similarities, as they both belong to the phylum Arthropoda. They both have a hard chitinous exoskeleton, a body with three or more segments and jointed legs. A major difference is their respiratory system. Crustaceans, having a largely aqueous background, have a set of gills in their trunk appendages. Insects have a network of trachea that lead to small valves (spiracles) in the sides of their body; a few primitive types breathe directly through the spiracles.
Habitat
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Crustaceans live almost exclusively underwater, from the ocean to freshwater pools, lakes and streams. The wood louse and its relatives live on land but are limited to moist environs such as the beach or under rotting logs, as their respiration depends upon air humidity to allow their gills to function. Insects are incredibly diverse in their choice of habitat, and can live in almost any ecosystem including fresh water, urban areas and anywhere with a temperate climate.
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Life Cycle
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Most insects, both flightless and flighted, undergo metamorphosis. Crustaceans reproduce exclusively through the sexual method. The offspring hatch as miniaturized adults. In most insect species, reproduction is also sexual; a male fertilizes a female's eggs, which in most species hatch into a larval form, often appearing different from the adult form. This larva later undergoes metamorphosis in order to attain its adult form. In other species, the eggs hatch into a miniature version of the adult.
Cuisine
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Lobster fishing is an industry important to Maine and the Canadian Maritimes. Lobster, crab, shrimp and crayfish are eaten across the world; lobster and crab especially can attain high prices. Insects are another story. North Americans and Europeans are still squeamish about the idea of eating insects, but the idea is well accepted in other parts of the world. Of flightless insects, grubs and mealworms are your best bet. They can be roasted, fried or ground into flour. Edible insects are much cheaper per gram than their crustacean counterparts.
Dangers to Humans
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Crustaceans are mostly harmless. Even the largest of the land crustaceans, the coconut crab (which can weigh up to 17 kilograms/37 lbs. and span 1 meter/39 in.), will only attack a human if it feels threatened. Insects can be far more deadly. Humans can be allergic to a multitude of insects' venom and bites, and even if the attack does not result in death, it can cause rashes, bumps and other sources of great discomfort.
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References
Resources
- Photo Credit beetle image by dwags from Fotolia.com Butterfly life cycle image by Matthew Cole from Fotolia.com lobster image by jedphoto from Fotolia.com
