NATURE NOTE - Number 48 July 14, 2022
Introduction:
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Our current topic: Arthropods – but not insects
Arthropods are a large grouping of interesting and wide spread animals that have two characteristics: jointed legs and an exoskeleton. An exoskeleton is an outer shell-like covering. They do not have a vertebrae, or backbone, like mammals, birds, fish, etc. The sub-group that quickly comes to mind is insects. We covered the huge insect class in the May 2021 NATURE NOTE (#21), but let’s discuss some of the many varied, but common, arthropods that are NOT insects that you might run into on your outings or at home.
Arachnids: Spiders, ticks, mites, scorpions, and daddy- long-legs all fall into this group. They look similar to insects, but they have 8 legs. Insects have only 6 legs. In addition to their legs, Arachnids often have a set of small “claws”, called palps to aid in capturing prey. Several of these are not people-friendly: spiders, ticks and scorpions (we don’t have these fortunately) so teach scouts to use a lot of caution around these.
Centipedes and millipedes: these are those many-legged critters you see crawling around on a moist forest floor or under bark or rotting wood.
Centipedes have at least 15 PAIR of legs, each pair attached to a body segment. They have the ability to deliver a painful bite, so be very careful with centipedes. Also, if you have seen a weird looking thing with many feathery long legs crawling around your basement near a drain, it’s likely a centipede.
Millipedes have 30 or more PAIRS of legs sticking out from under their shell-like body. There are 2 pairs per segment. They look a little like insect larvae, but larvae never have this many legs. They defend themselves from birds, their main predator, by emitting cyanide. Many millipedes in our area have a red or yellow edge to their dark body. There are at least 250 known species of millipedes in Virginia.
Crustaceans: Lobsters, crabs and crayfish all fall into this group, and fairly easy to recognize by their beady eyes, claws, and long antennae. Crayfish are common in our area streams. Crustaceans also include sow bugs, or pill bugs, those little armadillo-looking bugs that curl up into a ball when disturbed.
As a side note, worms, such as the common earthworm, are not Arthropods. They do not have jointed legs and belong to a separate Phylum of segmented worms called Annelida. Phylum is a large grouping used to classify animals and plants.
Nature Opportunities:
This is a good opportunity to teach scouts the importance of understanding how many animals and plants are classified for identification. Scientists have develop many, many rules for separating one group of similar-looking animals from another such as counting the legs to determine if it is an insect or not. Does it have more than 6 legs? Not an insect. This attention to detail is often needed to get to specific species. We won’t get into details here, but recognizing this need for detail is something scouts need to be aware of in identifying nature’s plants and animals.
Anything you as a scout leader can do to call attention of your scouts to the many facets of nature is good. Some might not be interested, true. But how much exposure do they get outside of scouting? Do what you can, when you can. Hopefully these NATURE NOTES will help you do that. Good luck!
