Arthropods (Phyla Arthropoda) Arthropods exhibit key feature…
Arthropods (Phyla Arthropoda) Arthropods exhibit key features and organ systems. Arthropods are segmented and exhibit an exoskeleton with muscles attached to the inside. The exoskeleton is molted during ecdysis, allowing the arthropod to grow. In some species, segments are fused into units called tagmata. Arthropods’ jointed appendages may be modified into mouthparts, antennae, or legs. Many arthropods have compound eyes composed of ommatidia; others have simple eyes (ocelli). An open circulatory system includes a muscular heart. The respiratory system in terrestrial arthropods comprises spiracles, tracheae, and tracheoles. The main components of the nervous system are an inhibitory brain and a ventral nerve cord. The excretory system of terrestrial hexapods, myriapods, and chelicerates consists of Malpighian tubules that eliminate uric acid or guanine. Spiders, mites, ticks, and horseshoe crabs (Chelicerata) have specialized anterior appendages. Chelicerates have specialized anterior appendages, the chelicerae, that function as fangs or pincers. Crabs, shrimps, lobsters, and barnacles (Crustacea) are largely marine organisms. Crustacea is characterized by a nauplius larva (figure 33.40). Crustaceans have three tagmata, and the two anterior ones fused to form a cephalothorax. Insects (Hexapoda) are the most abundant animals on Earth. The hexapods are extraordinarily diverse. Insects have three pairs of legs attached to the thorax and may have wings. They have highly developed sensory systems. Centipedes and millipedes (Myriapoda) have numerous legs. Centipedes have one pair of appendages per segment, whereas millipedes have two pairs. Screenshot 2025-03-09 at 11.50.17 PM.png
Read Details