Real Facts About Spiders
Posted: Thursday, April 26, 2007
by Anna Miller
natureday.com
Myth: Spiders are insects.
Fact: Actually, not everyone believes this. Around half of my callers did learn in school that spiders are not insects, but I find it rather appalling that the percentage is not higher. And how often, in mass media, we read or hear a phrase like "spiders prey on other insects!" Anyway, spiders belong to the Class Arachnida, insects to the Class Insecta. Arachnids are as distant from insects, as birds are from fish. It really is not a trivial distinction!
Fact: There are eleven orders of arachnids. These include the scorpions; mites and ticks; harvestmen; pseudoscorpions; whipscorpions; solpugids; and spiders. It's like the relation of beetles with insects: beetles constitute one order of insects, the Coleoptera, but not all insects are beetles. Similarly, not all arachnids are spiders.
Myth: You can always tell a spider because it has eight legs.
Fact: Not exactly. Scorpions, harvestmen, ticks, and in fact all arachnids - not just spiders - have four pairs of legs (see illustrations above). Insects have three pairs. Also, notice that I said "four pairs" instead of "eight." The number of leg pairs (one pair per leg-bearing segment) is more significant than individual legs, which can be lost.
Myth: All spiders make webs.
Fact: Technically, a web is not just anything a spider makes out of silk; it is a silk structure made to catch prey.
Only about half of the known spider species catch prey by means of webs . actively hunt for prey (including members of the wolf spider, jumping spider, ground spider, sac spider, lynx spider, and other spider families), or sit and wait for prey to come to them (trap door spiders, crab spiders, and others).
Hunting spiders use their silk for the dragline (the single thread all spiders leave behind them when they walk), the egg sac, and in some species, the retreat (a little silk "house" the spider rests in), , but do not make true webs.
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Top-level comments on this article: (1 total)I need School Spiders Facts For School Or I Will Get A Bad GRADE
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