Slithering Centiworm

The slithering centiworm split from it's ancestor, and has spread it's range to the Nuke river. It hasn't changed much, other than having it's bristles have develop into teeth as well as having gone parasitic. To catch a host to feed blood from, it waits for any animal between 40 cm and 3 m long, (the bigger, the better) and attacks, sucking blood out of it's host until it has had it's fill. Afterwards it just slithers down to the ground. Smaller animals would be too small for a blood meal. It has developed 3 primitive eyes so it can detect prey. Every year, slithering centiworms gather in mass by the side of Nuke river to breed. To mate, the 3 genders mount on each other, and expels it's reproduction process. They still require 1 Sperm, 1 Egg, and 1 Hormone Cell. Instead of releasing spores into the soil, it lays thousands of soft eggs in the water. They each live about 15 years excepting predation.