Presentation on theme: "An unknown animal you’ve passed before. . . By Nick Yeh"— Presentation transcript:
1An unknown animal you’ve passed before. . . By Nick Yeh The Water BearAn unknown animal you’ve passed before. . .By Nick Yeh
2Classification Kingdom: Animalia Phylum: Tardigrada Class: HeterotardigradaOrder: EchiniscoideaFamily: EchinisidaeGenus: EchiniscisSpecies: (over 800!)Scientific Name: TardigradaCommon Name: Water Bear
3Description Multicellular invertebrates Microscopic bear w/claws (moves like a bear)Have brain, legs, nerves, mouth, & eyesSmaller by a factor of 100 compared to humansSize: mm(200 microns)Weight: not available
4Description…continued Have precise muscle control like larger animalsEat white cushion moss, predatory nematode, rotifer, and green algaeNematodes eat water bearsBreak down lichens, mosses, and waterHarmless to humans!
5Cryptobiosis Death-like state where they suspend their metabolism Other organisms usually die when they do this!Their metabolism decreases to less than 0.01% of normal and the water content in their bodies decreases to less than 1%Naturally, water bears can stay in this state for 12 years, but in labs they have lived up to 100 years and still showed signs of life. Theoretically, if they are frozen in this state, they can live forever!
6Forms of CryptobiosisThere are four forms of cryptobiosis: anhydrobisis, cryobiosis, osmobiosis, and anoxybiosisAnhydrobiosis-initiated by desiccation (studied the most)used in limno-terrestrial habitats (like mosses)involves complete water loss and a tun formation which leaves the water bear folded and constricteduses metabolism and trehelose, a protective sugarrevival time depends on the time spent in anhydrobiosisCryobiosis-initiated by temperatures below 0C (32F)orders freezing of body waterOsmobiosis-initiated by need for waterAnoxybiosis-initiated by need for oxygen
7Super Water Bear When in cryptobiosis they are… Nearly indestructible! Able to withstand 150C (302F) and almost absolute zero (-272.8C) or (-459F) which has no free molecular vibration and where no organism’s metabolism can surviveResistant to x-rays of 570,000 Roentgens whereas 500 Roentgens are fatal to usResistant to vacuums like outer space, a few noxious chemicals, boiling alcohol, and pressures that are six times greater than the bottom of the deepest ocean
8Reproduction Reproduce sexually Period: n/a Produce anywhere from 1-30 eggs at a timeFrequency of birth: n/aEgg size: 100 microns
9Where Are they? Can live almost anywhere! Prefer to live in white cushion moss, green algae, British soldiers (a type of lichen), and common greenshield (type of lichen).You can see water bears for yourself…soak moss or lichen sample in water for a few hours and shake or squeeze to release any water bears in sampleexamine water released under microscope with at least 30x power (you can also use a hand lens)
10Other Details Closest Relations… Like arachnids because of eight legs Similar characteristics to nematodes & crustaceansLife Expectancy…No exact life expectancyMinimum in a culture dish is one yearThe desiccation period can last seven years