Anthropods - Anthropods Phylum Onychophora Velvet worms -...

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Anthropods Phylum Onychophora Velvet worms - Comprised of 60% - plants, animals, bacteria; everything! - The missing link between annelids and anthropods - Segmented appendages (feet and legs) - Secrete glue in a jet like fashion Phylum Tardigrada Water bears - Small, short, stubby - Live on moss and algae to feed on them - Set of 4 appendages - Transparent body - Cryptobiosis ( cryptic = camouflage ) o suspended animation – an ability to withstand extreme conditions in which they tend to lose 98% of their water mass o can be exposed to zero gravity, space radiation, and zero oxygen and still live Phylum Anthropoda ( Anthro = jointed )( poda = legs ) ~ jointed legs - largest phylum with respect to the number of species because they can be “successful” o “successful” – known be available in all environments - Snowfleas – exist in extreme cold temperature - Small unless marine due to their exoskeleton which limits their size o In water, the exoskeleton will have a higher pressure onto the body o Therefore, marine anthropods have no exoskeleton - Body Plan o Segmented into metameres o Jointed appendages moved by the Complex Muscular System o Hemocoelum – body cavity is one large cavity - Circulatory System o Open o Similar aorta but functions as an open pump to keep the blood pumping through the body - Digestive System o Complete (mouth to anus) - Brain structure o Dorsal Brain Located dorsally and anteriorly o Contains only the ventral nerve cord o Brain considered inside out and upside down Inside out – brain on the outside of the exoskeleton Upside down – nerve cord run through the belly - Nervous system o Aquatic = gills o Simple diffusion o Trachea Trachae system – deliver oxygen openly and directly to the cells o Book gills - Sensory organs o Highly developed o Antenna – sense of smell
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o Parts per million senses of chemicals Flies have chemoreceptors on their feet = taste bud on their feet - Behavioral Patterns o Metamorphasis – can molt (shed) the exoskeleton o Emerge and ?? - Subphylum Trilobita (Trilobites) o Extinct group of about 200 million years o Pyridium – Head, thorax, abdomenlike (not segmented at the tail end) - Subphylum Chelicerata o Includes the spider o Chelcerae 1 st arrangement of the mouth Heads having appendages around the mouth part Used as feeding structures – modified into fangs o Pedipalps 2 nd arrangement of the mouth Second pair of appendages In spiders – used to communicate with females In scorpions – pinchers used o No antenna, no mandibles (jaw like structures) o Cephlothorax = Head + thorax Cephlothorax + abdomen ~ usually segmented but not always - Class Merostoma Horseshoe crab o Contains Carapace, Pedipalps, Chelcerae, Book gills Telson Tail that serve as a balance Compound eyes Contains subunit eyes ( ommitidia ) 5 pairs of walking legs indicates primitive nature o scavengers that come onto the land to breed
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Anthropods - Anthropods Phylum Onychophora Velvet worms -...

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