Marine worm

[2] This method is driven by the biological disadvantages (such as resource need and energy expenditure) behind carrying offspring instead of the more prolific gene passage through multiple impregnations.

[citation needed] Polynoid scale worms are estimated to have arrived in deep sea ecosystems around sixty million years ago.

[3] Marine worms can be herbivores, carnivores, parasites, detritivores, or filter feeders, but many strange examples of feeding are seen in this diverse type of animal.

For example, in platyhelminths this is achieved through diffusion of oxygen (as well as other nutrients) across a moist epithelial layer, whereas annelids have a closed circulatory system with blood vessels lining the body.

These specialized tentacles allow for gas exchange, further decreasing oxygen content in dead zones and in shallow water, which encourages plant and algae growth.

[citation needed] This quality is also observed in deeper oceans, where tube worms that use respiratory plumes with tentacles perform gas exchange of hydrogen sulfide and methane around hydrothermal vents.