Arthropods Questions PDF

ARTHROPODS: What percentage of animals are arthropods? 75% How many described species of Arthropods are there? 1.2 million What subphylum do insects belong to? Hexapoda What subphylum do spiders, scorpions, mites, horseshoe crabs, and sea spiders belong to? Chelicerata What subphylum do shrimps...

ARTHROPODS: What percentage of animals are arthropods? 75% How many described species of Arthropods are there? 1.2 million What subphylum do insects belong to? Hexapoda What subphylum do spiders, scorpions, mites, horseshoe crabs, and sea spiders belong to? Chelicerata What subphylum do shrimps, crabs, copepods, barnacles belong to? Crustacea What subphylum do centipedes and millipedes belong to? Myriapoda What subphylum do trilobites belong to? Trilobita Are trilobites extinct? Yes What did arthropods arise from? Panarthropods What are panarthropods? Onychophorans and Tardigrades What is the most ancient group of Arthropods? Crustaceans What was the first group of Arthropods to move onto land and in what era? Chelicerates in the Ordovician era What era did Myriapods move onto land? Silurian era What era did Hexapods move onto land? Devonian era Which group of Arthropods was most successful at colonizing the land? Hexapoda What did hexapods evolve from? Crustaceans What are the characteristics of arthropods? 1. Bilaterally symmetrical and triploblastic 2. Segmented with jointed legs 3. Chitinous exoskeleton 4. Skeleton moulted during growth 5. Dorsal anterior brain and ventral nerve cord 6. Well developed sensory organs associated with cephalization 7. Coelomate although coelom is reduced 8. Gut is complex with specialized regions 9. Move using skeletal muscle attached to exoskeleton 10. Vascular system is open, but degrees of development 11. Various excretory organs depending on habitat 12. Reproduction – nearly all dioecious with indirect, mixed and direct development 13. Range in size from microscopic to 4m 14. Homologous structures = 2nd antennae of crabs = chelipeds of scorpions Why did the legs of arthropods become jointed? Exoskeleton restricted movement What is the function of the exoskeleton in Arthropods? - Provides protection from predators - Allows it to be a predator What is the layered cuticle secreted by underlying epidermis in Arthropods? Hypodermis What is the thin outer layer of the exoskeleton in Arthropods? Epicuticle What is the thick inner layer and what is it made out of in Arthropods? Procuticle - made of chitin-protein What is the epicuticle and which arthropods possess it? Terrestrial arthropods, such as insects - waxes that aid in reducing evaporative water loss What is the exocuticle in Arthropods? Thicker layer consisting mainly of chitin and proteins What is the endocuticle in Arthropods? The inner layer of the cuticle What are jointed legs in Arthropods? Segmented legs in arthropods What separates the segments in jointed legs in Arthropods? Arthrodial membranes What have some jointed legs of Arthropods evolved into? mouthparts, gill cleaners and pincers What is moulting in Arthropods? the old cuticle splits and the animal pulls itself out. All linings shed including gut and all other linings are renewed. Old exoskeleton is left behind and the new emerging arthropod is still very soft and unhardened What is a pre-moult stage in Arthropods? active secretion of hormones and breakdown of old endocuticle occurs. In crustaceans de-calcification may occur. Loosening of old cuticle What secretes the new cuticle in Arthropods? Epidermis What is the post-moult in Arthropods? hardening of the cuticle How long can the post-moult take in Arthropods? Hours to weeks Do Arthropods have a complete or incomplete digestive tract? Complete What does the foregut do in Arthropods? mechanical and chemical breakdown What does the midgut do in Arthropods? chemical breakdown and absorption What does the hindgut do in Arthropods? water absorption and preparation of feces Do Arthropods have an open or closed circulatory system? Open What type of heart do Arthropods have? Tubular dorsal heart What is arthropod blood called? Hemolymph What does hemolymph do in Arthropods? transports gases as well as nutrients, wastes and hormones What does hemolymph not transport in insects? Gases What are the pigments in arthropod blood? Hemocyanin and hemoglobin How do terrestrial arthropods perform gas exchange? book lungs or branching tubules – tracheal system or pseudotrachea What are book lungs in Arthropods? pages' of thin membranes referred to as lamellae. The lamellae possess air pockets through which hemolymph flows What is a tracheal system in Arthropods? tubes made of a polymeric material called chitin. Insect bodies have openings, called spiracles, along the thorax and abdomen What is pseudotrachea in Arthropods? one of a series of chitinous tubes through which liquid food is taken into the mouth. How do aquatic arthropods perform gas exchange? Gills or across the body surface using diffusion Where is the ventral nerve cord in Arthropods? along body and into segments What are mechanoreceptors in Arthropods? detect stimuli such as touch, pressure, vibration, and sound from the external and internal environments Where are mechanoreceptors located in Arthropods? Extend through the cuticle and associated with nerve endings What are examples of mechanoreceptors in Arthropods? setae, bristles and sensilla What types of eyes can arthropods have? simple to eyespots to highly elaborate compound eyes on moveable stalks Are most arthropods dioecious or monoecious? Dioecious Are most arthropods internal or external fertilizers? Internal What are the types of development in arthropods? Indirect, mixed and direct development What are the types of development in arthropods dependent on? Their environment