**whole surface by diffusion
***tick living in 400m depth of seawater
==tick==
*eyes are on frontal edge near the roots of the first pair of legs
*scutum (hard shell)
**covers whole back of male
**covers only frontal part of female by which female can pool mammal blood
*parity
**hard tick is semelparity (single oviposition)
**soft tick is iteroparity (multiple ovopositions)
*tick live years, mostly 2-3 years, at longest 7 years