Arthropoda include insects, crustaceans and arachnids. Arthropods form the phylum Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans. Other types of arthropods produce silk, most notably various arachnids, such as spiders. Fully terrestrial life evolved, including early arachnids, fungi, and centipedes. Fully terrestrial life evolved, which included early arachnids, fungi, and centipedes. Its diet includes invertebrates such as beetles, moths, butterflies, arachnids, and snails. They form a phylum which includes insects, arachnids, myriapods, and crustaceans. Spermatophores are the norm in arachnids and several soil arthropods. Enemies come in the form of insects, mollusks, reptiles, amphibians, and arachnids. Scorpions are predatory arachnids of the order Scorpiones. Animal studies mostly focus on fish, insects, birds, amphibians and arachnids. Arachnophobia is an intense and unreasonable fear of spiders and other arachnids such as scorpions. Both spiders and scorpions include contenders for the largest arachnids. Sexual cannibalism is common among insects, arachnids and amphipods. Spiders and scorpions are members of one chelicerate group, the arachnids.