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WS_Science By You Activity_Bear Trap

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+ ward ' s science Page 2 Important Facts: Size/description .1 to 1.5 mm/4 pair of legs with 4–8 claws on each/segmented body Habitat Lichens, mosses, sand dunes, soil, sediments, and leaf litter; can survive extreme conditions but not considered extremophiles because they are not adapted to live in these conditions; require a thin layer of water around the body in order to perform all life functions. Feeding Some herbivores and some are carnivores yet both feed on body fluids of prey; mouthparts vary per species and diet; stylet mouthpart pierces cell and pharynx sucks the fluid that spills out. Reproduction and Fertilization Separate sexes most with external fertilization; some species can reproduce asexually and undergo parthenogenesis. Taxonomy Kingdom Animalia Phylum Tardigrada 900+ identified species New Research • Evolved ability to denature unnecessary proteins in extreme environmental conditions • Protective genes code for proteins called Dsup that protect delicate DNA • Enter a state of cryptobiosis (metabolic activity is in a reversible standstill) • In many conditions, they survive by going into an almost death-like state called cryptobiosis. They curl into a dehydrated ball, called a tun, by retracting their head and legs. If reintroduced to water, the tardigrade can come back to life in just a few hours. • While in cryptobiosis, tardigrades' metabolic activity gets as low as 0.01 percent of normal levels, and their organs are pro- tected by a sugary gel called trehalose. They also seem to make a large amount of antioxidants, which may be another way to protect vital organs. Water bears also produce a protein that protects their DNA from radiation damage. • In cold temperatures, they form into a special tun that prevents the growth of ice crystals. Bear Trap: Finding Tardigrades (continued) Use a microscope to view tardigrades in collected sample water. Students can use phone held up to microscope eyepiece to capture tardigrades within their sample.

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