What is an Arthropod?
Definition: have a segmented body, a tough exoskeleton, and jointed appendages.
Definition: have a segmented body, a tough exoskeleton, and jointed appendages.
Body Plan:
Arthropods use complex organs systems to carry out different essential functions. For example, the digestive system breaks food into nutrient molecules, which then move into blood in the circulatory system. The blood carries the nutrients to body cells. Feeding: They include herbivores, carnivores, and omnivores. There are arthropod bloodsuckers, filter feeders, detritivores, and parasites. Their mouthparts range from pincers or fangs to sickle-shaped jaws that can cut through the tissues of captured prey. Respiration, Excretion & Circulation: Most of the terrestrial arthropods breathe through a network of branching tracheal tubes that extend throughout the body. Air enters and leaves the tracheal tubes through spiracles. Other terrestrial arthropods, such as spiders, respire using book lungs. Most aquatic ones, such as lobsters and crabs, respire through featherlike gills. The horseshoe crabs, however, respire through organs called book gills. Arthropods have an open circulatory system. Most terrestrial arthropods, such as insects and spiders, dispose of nitrogenous wastes using Malpighian tubules. In aquatic ones, diffusion moves cellular wastes from the arthropod's body into the surrounding water. |
Response:
Most arthropods have well-developed nervous system. They all have a brain. Most have sophisticated sense organs, such as compound eyes for gathering information from the environment. Reproduction: Terrestrial arthropods have internal fertilization. Aquatic ones may have internal or external fertilization. |
Trilobitomorpha
A typical primitive arthropod was composed of many identical segments, each carrying a pair of appendages. It's body probably closely resembled that of a trilobrite. This early body plan was modified gradually. The appendages gained included antennae, claws, walking legs, wings, flippers, mouthparts, tails, and other specialized structures. The evolution of arthropods, by natural selection and other processes, has led to fewer body segments and highly specialized appendages for feeding, movement, and other functions.
A typical primitive arthropod was composed of many identical segments, each carrying a pair of appendages. It's body probably closely resembled that of a trilobrite. This early body plan was modified gradually. The appendages gained included antennae, claws, walking legs, wings, flippers, mouthparts, tails, and other specialized structures. The evolution of arthropods, by natural selection and other processes, has led to fewer body segments and highly specialized appendages for feeding, movement, and other functions.
Arachnida
Arachnids have mouthparts called celicerae and two body sections and nearly all have four pairs of walking legs.
Arachnids have mouthparts called celicerae and two body sections and nearly all have four pairs of walking legs.
Crustacea
Crustaceans typically have two pairs of antennae, two or three body sections, and chewing mouthparts called mandibles.
Crustaceans typically have two pairs of antennae, two or three body sections, and chewing mouthparts called mandibles.