Heterokrohnia involucrum Dawson, 1968
A near-bottom bathypelagic arrow worm
Size
- body up to 3.5 cm
Color & Characteristics
- Body firm & semi translucent, gut often orangish, eyes absent
- 1 pair of medium length fins spaning trunk and tail, with incomplete rays
- Head and body broad, tail 30-40% of length
- Each side of head with 10-12 non-serrated hooks, 22 anterior and 34 posterior teeth
- Collarette long and frothy in larger specimens, reduced on smaller individuals
- Neck canals present, sensory hairs obvious along body
- Semininal vesicles conical, touching posterior fin but separated from tail fin
- Ovaries of medium length, with large eggs
Habitat
- Bathypelagic, usually within 100 m of seafloor, and often within 10-20 m of it
- Only known from the Arctic
Feeding
- An ambush predator, detecting motion with numerous tiny hairs along body
- Pey seized with hooks during a rapid lunge, ratched whole down throat with aid of teeth
- Prey size largely determined by head width
- Diet unknown, likely composed of copepods, possibly ostracods, and larvaceans in lower numbers - close proximity to seafloor suggest epibenthic prey, as does high sediment content in gut.
Life cycle
- Protandrous (releasing sperm first, then producing eggs)
- Fertilized eggs likley released as stickly masses
- Generation time and life expectancy unknown
Page Author: Russ Hopcroft
Created: November 15, 2011
