1. Tardigrada KIM, WOOSOO BSBIO2A

2. Phylum: Tardigrada Water Bears First discovered in 1773 First discovered in 1773 800 spp 800 spp 0.1-0.5mm in length 0.1-0.5mm in length Widespread Widespread Live in semi aquatic habitats, water film Live in semi aquatic habitats, water film Cryptobiotic, some are cyclomorphic Cryptobiotic, some are cyclomorphic Temp range from +149C to - 272C, withstand high vacuum, high UV, long periods without O 2 Temp range from +149C to - 272C, withstand high vacuum, high UV, long periods without O 2 Dessication for > 120 years: back to life in hours Dessication for > 120 years: back to life in hours

3. Characteristic 1)Bilaterally symmetrical. 1)Bilaterally symmetrical. 2)Body has more than two cell layers, tissues and organs. 2)Body has more than two cell layers, tissues and organs. 3)Body cavity is partially a coelom. 3)Body cavity is partially a coelom. 4)Most possesses a through straight gut with an anus. 4)Most possesses a through straight gut with an anus. 5)Body monomeric. 5)Body monomeric. 6)Body possesses 4 pairs of unjointed claw bearing legs. 6)Body possesses 4 pairs of unjointed claw bearing legs. 7)Body possesses a fixed number of cells (eutelic). 7)Body possesses a fixed number of cells (eutelic).

4. 8)Has no circulatory or respiratory system. 8)Has no circulatory or respiratory system. 9)Primitive excretory organs in some species. 9)Primitive excretory organs in some species. 10)Reproduction normally sexual and gonochoristic, but can be parthenogenetic. 10)Reproduction normally sexual and gonochoristic, but can be parthenogenetic. 11)Feed on a plants or small animals. 11)Feed on a plants or small animals. 12)All live in aquatic or damp places, normally associated with vegetation. 12)All live in aquatic or damp places, normally associated with vegetation.

5. Classfication Kingdom: Animalia Kingdom: AnimaliaAnimalia Superphylum: Ecdysozoa Superphylum: EcdysozoaEcdysozoa (unranked): Panarthropoda (unranked): PanarthropodaPanarthropoda Phylum: Tardigrada Phylum: Tardigrada

6. Physiology Tardigrades have been known to withstand the following extremes while in this state: Tardigrades have been known to withstand the following extremes while in this state: Temperature – tardigrades can survive being heated for a few minutes to 151 °C. Temperature – tardigrades can survive being heated for a few minutes to 151 °C. Temperature Pressure – they can withstand the extremely low pressure of a vacuum and also very high pressures, more than 1,200 times atmospheric pressure. Pressure – they can withstand the extremely low pressure of a vacuum and also very high pressures, more than 1,200 times atmospheric pressure. Pressure vacuum atmospheric pressure Pressure vacuum atmospheric pressure Dehydration – tardigrades have been shown to survive nearly 10 years in a dry state. When encountered by extremely low temperatures, their body composition goes from 85% water to only 3%. As water expands upon freezing. Dehydration – tardigrades have been shown to survive nearly 10 years in a dry state. When encountered by extremely low temperatures, their body composition goes from 85% water to only 3%. As water expands upon freezing. Dehydration

7. Radiation – tardigrades can withstand median lethal doses of 5,000 Gy (of gamma-rays) and 6,200 Gy (of heavy ions) in hydrated animals (5 to 10 Gy could be fatal to a human). Radiation – tardigrades can withstand median lethal doses of 5,000 Gy (of gamma-rays) and 6,200 Gy (of heavy ions) in hydrated animals (5 to 10 Gy could be fatal to a human). RadiationGy RadiationGy Environmental toxins – tardigrades can undergo chemobiosis—a cryptobiotic response to high levels of environmental toxins. However, these laboratory results have yet to be verified. Environmental toxins – tardigrades can undergo chemobiosis—a cryptobiotic response to high levels of environmental toxins. However, these laboratory results have yet to be verified.toxinscryptobiotictoxinscryptobiotic

8. Metabolism Tardigrades exchange gases through their cuticle. The substances taken up by diffusion are often stored in storage cells that are found in the body fluid. Tardigrades exchange gases through their cuticle. The substances taken up by diffusion are often stored in storage cells that are found in the body fluid. Tardigrades do not have a circulatory system; the fluids are moved around the body cavity by the movement of the animal. Tardigrades do not have a circulatory system; the fluids are moved around the body cavity by the movement of the animal. Osmoregulation is accomplished by the Malpighian tubules located at the midgut-hindgut junction. Osmoregulation is accomplished by the Malpighian tubules located at the midgut-hindgut junction.

9. Ecology Tardigrades occur in marine, freshwater and terrestrial habitats worldwide. Tardigrades occur in marine, freshwater and terrestrial habitats worldwide.marine They live in a wide variety of habitats including soils, leaf litter, moss, lichens, flowering plants, algae and even in hot springs. Some tardigrades live on the legs of isopods, on the gills of mussels or as parasites on the epidermis of barnacles or holothurians. They live in a wide variety of habitats including soils, leaf litter, moss, lichens, flowering plants, algae and even in hot springs. Some tardigrades live on the legs of isopods, on the gills of mussels or as parasites on the epidermis of barnacles or holothurians.soilslichensparasitessoilslichensparasites

10. Idiosyncratic Inverts When environmental conditions start to deteriorate, tardigrades enter a latent state until conditions improve. When environmental conditions start to deteriorate, tardigrades enter a latent state until conditions improve. Encystment - A latent state in which resistant cysts are produced. Freshwater tardigrades in permanent water habitats enter this state when environmental conditions deteriorate. These cysts can't withstand high temperatures, but can survive a year without food. Encystment - A latent state in which resistant cysts are produced. Freshwater tardigrades in permanent water habitats enter this state when environmental conditions deteriorate. These cysts can't withstand high temperatures, but can survive a year without food.FreshwaterhabitatsFreshwaterhabitats Anoxybiosis - A latent state that is induced by low oxygen concentrations in the surrounding water. In this state tardigrades become immobile, transparent, rigid and extended Anoxybiosis - A latent state that is induced by low oxygen concentrations in the surrounding water. In this state tardigrades become immobile, transparent, rigid and extended

11. Cryobiosis - If cooled gradually, tardigrades form a cold-resistant tuns which allows the animal to survive being frozen. Cryobiosis - If cooled gradually, tardigrades form a cold-resistant tuns which allows the animal to survive being frozen. Osmobiosis - Tun production induced by elevated osmotic pressure and decreased water availability. For example, a freshwater tardigrade placed in salt water will form a tun. Osmobiosis - Tun production induced by elevated osmotic pressure and decreased water availability. For example, a freshwater tardigrade placed in salt water will form a tun.salt watersalt water Anhydrobiosis - Tun production in terrestrial tardigrades that is induced by evaporative water loss. If the tardigrade dehydrates too quickly, it will not survive. Anhydrobiosis - Tun production in terrestrial tardigrades that is induced by evaporative water loss. If the tardigrade dehydrates too quickly, it will not survive.terrestrialevaporativeterrestrialevaporative

12. Reproduction Most tardigrades reproduce parthenogenetically, but a few reproduce sexually. Most tardigrades reproduce parthenogenetically, but a few reproduce sexually. Some species are simultaneous hermaphrodites, which are able to fertilize themselves, but sequential hermaphroditism is more common. Some species are simultaneous hermaphrodites, which are able to fertilize themselves, but sequential hermaphroditism is more common. Both males and females have only one gonad, and it lies dorsal to the intestine. Both males and females have only one gonad, and it lies dorsal to the intestine.

13. Species of Tardigrada Hypsibius Hypsibius is a genus of water bear or moss piglet, a tardigrade in the class Eutardigrada. is a genus of water bear or moss piglet, a tardigrade in the class Eutardigrada.tardigrade Eutardigradatardigrade Eutardigrada Kingdom: Animalia Kingdom: AnimaliaAnimalia Phylum: Tardigrada Phylum: TardigradaTardigrada Class: Eutardigrada Class: EutardigradaEutardigrada Order: Parachaela Order: ParachaelaParachaela Family: Hypsibiidae Family: HypsibiidaeHypsibiidae Subfamily: Hypsibiinae Subfamily: HypsibiinaeHypsibiinae Genus: Hypsibius Genus: Hypsibius

14. Echiniscoides sigimunde Water bear Water bear Kingdom - Animalia Kingdom - AnimaliaAnimalia Phylum - Tardigrada Phylum - TardigradaTardigrada Class - Heterotardigrada Class - HeterotardigradaHeterotardigrada Order - Echiniscoidea Order - EchiniscoideaEchiniscoidea Family - Echiniscoididae Family - EchiniscoididaeEchiniscoididae Genus - Echiniscoides Genus - EchiniscoidesEchiniscoides