Colossendeidae is a family of sea spider (class Pycnogonida). Roughly 20% of the sea spider species in the world are from Antarctic waters. A partial genome of a flavivirus has been found in the sea spider "Endeis spinosa". Colossendeis is a genus of sea spider (class Pycnogonida) belonging to the family Colossendeidae. Pycnogonum stearnsi or Stearns' sea spider is a marine arthropod in the family Pycnogonidae.