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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.
