3rd DepEx (Arthropod gen. info.)

• Form and Symmetry

  Bilateral, tagma (head, thorax, abdomen)
• Arthropoda are animals with visible segmentation/jointed appendages
• The 8 segments of arthropods are: coxa, trochanter, femur, patella, tibia, metatarsus, tarsus, & pre-tarsus
• Integumentary

  simple with cuticular secretions
• Skeletal

  chitinous exoskeleton which is secreted by the hypodermis and is composed of overlapping plates; maybe with calcium carbonate (CaCO3)
• Skeletal

  Procuticle endoskeleton with appendages being externally jointed
• Muscular

  striated muscle bundles attached to procuticle
• Respiratory

  tracheal systems; book gills or lungs
• Digestive

  complete (with foregut, midgut, andhindgut)
• Circulatory

  open
• Heart with ostia - enables blood to flow into the heart from the pericardium
• What is the role of ostia?

  It enables blood to flow into the heart from the pericardium
• Blood components: amoebocytes, hemocyanin (repiratory pigment)
• Direction of blood flow

  heart → arteries → sinuses (which bathe the tissues) → pericardium → heart
• Excretory

  malpighian tubules and /or coxal glands; maxillary glands
• Nervous

  cephalize with 1 or 2 pairs of antennae or none
• What is the nervous system composed of?

  Large brain and well-developed sense organs (eyes and antennae)
• Reproduction

  sexual with metamorphosis present; mostly dioecious

  Fertilization: external for aquatic, internal for terrestrial
• Members comprise >90% of the animal kingdom. Most successful of all animal groups because it is the largest and most diverse phylum.
• Arthropods are also called invertebrates with jointed legs
• Habitat

  aerial, terrestrial, or aquatic
• Terrestrial or land is the most suitable environment
• They are schizocoelomate (coelom involved with circulatory system), triploblastic, and bilaterally symmetrical
• Metamerism


  segmentation; evident in arthropods embryonic development and conspicuous feature of many adults
• Tagmatization


  resulted from the fusion of metamere, with 5 segments fused into a head, the next 3 into the thorax, and remainder to the abdomen
• Cephalothorax


  fusion of head and thorax
• Opisthosoma


  fusion of thorax and abdomen
• Molting or Ecdysis


  mechanism by which arthropods discard their undersized "shells" and are replaced with a larger one
• Medical importance

  antiseptics, used in human-made products, biological vectors of pathogens, frequent cause for clinical attention
• Economic importance


  pest, food, pollination
• Ecological

  Ecological keystone species - species with large effects on the communities it inhabit