February 2013

Anemonefish behavior at night appears to oxygenate sea anemone hosts and to augment the metabolism of both partners

Anemonefish oxygenate their anemone hosts

US researchers measured and compared the net dark oxygen uptake of fish–anemone pairs when partners were separate from each other, together as a unit, and together as a unit but separated by a mesh screen that prevented physical contact.

They found that both the fish and anemones consumed 1.4 times more oxygen when they were together than when apart.

"Anemone oxygen consumption increases with water flow, suggesting that any flow-related side effects of clownfish behaviour will indeed increase anemone breathing rates."

"Shhh! - can you turn that down a notch?" Crabs fare better with a bit of peace and quiet

Noise affects crabs

A team from the Universities of Bristol and Exeter exposed crabs to recordings of ship noise and found it affected their metabolism—indicating elevated stress—and found little evidence that crabs acclimatise to noise over time.

Ship noise is the most common source of noise in the aquatic environment.

If commercially important crabs and lobsters are affected by noise, these findings have implications for fisheries in busy shipping areas where large individuals may be losing out.

The nudibranch Chromodoris reticulata sheds and regrows its penis between matings.

Nudibranch sheds penis after sex

Nudibranchs are hermaphrodites, meaning that they carry both male and female reproductive organs. Moreover, when they mate, they can perform the male role of donating sperm and the female role of receiving sperm at the same time.

The scientists observed sex between sea slugs that they had captured during scuba dives and held in a tank.

It goes both ways

This process involves two penises and two vagina-like organs, and sperm transmission effectively happens simultaneously during the encounter.