CAS BB 191 Lecture Notes - Lecture 9: Malpighian Tubule System, Ecdysis, Book Lung
Document Summary
The arthropods, largest phylum of animals in the world. Includes: spiders, mites, scorpions, ticks, crustaceans, millipedes, centipedes and insects. Excretory system of malpighian tubules in some; coxal, maxillary or antennal glands in others. Nervous system of annelid plan with highly developed sensory organs. Sexes usually separate, metamorphosis in some, internal fertilization, growth with ecdysis (molting) Reasons for success: a versatile exoskeleton, segmentation and appendages for more efficient locomotion, air piped directly to tissues, highly developed sensory organs, complex behavior, reduced competition for resources through metamorphosis. Indirect development: the larval or juvenile stage does not resemble the adult. The molting of the cuticle to accommodate growth, generally occurs between developmental stages. Epicuticle: outer, thin layer of protein and lipids. Procuticle: inner, thicker layer of chitin and protein. Subphylum chelicerata: spiders, ticks, mites, scorpions, horseshoe crabs. Six pairs of appendages: pair of chelicerae, pair of pedipalps, four pairs of walking legs. Chelicerae function as fangs and deliver poison.