similarities between arachnids & insects?

pleaseplease anyone knws the similarities between arachnids & insects?

8 Answers

  • 1 decade ago
    Favorite Answer

    Arachnids and insects (and crustaceans) are arthropods, and therefore share several characteristics. They both have jointed limbs. Their bodies are organized into segments, arachnids have a cepalathorax and an abdomen and insects have a head, thorax and an abdomen. They both have a hard outer shell made of chitin (sometimes also called an exoskeleton) which they shed periodically to allow for growth.

    Even though wikipedia usually gets a bad rap, the entry for arthropods is quite good and contains many references if you want to read a bit more. Also, Animal Diversity Web has some good info.

  • 4 years ago

    The reason they are grouped in different classes within Arthropoda is because they are descendants of different ancestors. This fact is reflected in their structural differences. The arachnids are more closely related to the horseshoe crabs than they are to the insects. Together the arachnids and Merostomata (horseshoe crabs) form the subphylum Chelicerata, because they all have a pair of chelicerae, which are the only appendages that are found before the mouth. Scientists, at least the good ones, try to look beyond the superficial similarities that are the result of adaptation to a similar environment and look instead for more fundamental similarities that are informative of common ancestry. For example, scientists tend to overlook the fact that bats and birds both have wings, and look instead at their body coverings. They see that birds have feathers, but bats do not. Bats instead have hair, like other mammals. The wings of bats and the wings of birds are simply superficial similarities that are similar because they allow birds and bats to fly. The similarities are superficial because bat wings are constructed from skin membranes that are stretched over 5 elongated fingers, whereas bird wings are constructed from feathers, and they are attached to the forelimbs of birds, in addition to one of the fingers, while the remaining two fingers of birds are not very prominent and not involved with supporting the wings. Even though spiders look superficially more like insects than the horseshoe crabs, scientists nevertheless have figured out that spiders are in fact more closely related to the horseshoe crabs than they are to insects.

  • 1 decade ago

    The similarities are obvious; they are both arthropods. It is the differences that are interesting. Insects usually have three pair of mouth parts: a pair of chewing mandibles and two pair of maxilla, used to taste and hold food (these can be greatly modified in the different insect groups) and three pair of legs. Spiders have fangs (called chelicerae in other arachnids) pedipalps, used to hold their food (and mate in male spiders) and their four pairs of legs.

    Source(s): Brusca & Brusca, Invertebrates
  • 1 decade ago

    First, they are arthropes. Arthropods includes crustaceans, insects, myriapods, and arachnids. Arthropod means jointed foot. Both have jointed legs and segmented bodies.

    Second, both have jointed legs. The legs are connected to th thorax. The legs are not connected to the head.

    Last is they both have segments.

    good luck.

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  • 3 years ago


  • Anonymous
    1 decade ago


  • 1 decade ago

    ask a spider

  • Anonymous
    5 years ago

    god thank you

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