Photo of the day (77): egg laying of Phyllidia flava

Those are two marine slugs Phyllidia flava laying eggs. This is ventral view showing the foot of snails in an aquarium. Both of them are laying a spiral ribbon of eggs:
Phyllidia flava laying eggsThis species of sea slug is orange and its eggs are also orange. But you are lucky to see its eggs so clearly like this, because it usually lays eggs on the Axinella cannabina sponge, which is also orange.

It is a “camouflage” in general. This type of camouflage, when the animal visually resemble its surrounding is called “crypsis”. It is a “visual crypsis” and the animal has “cryptic coloration”.

Detail of the bigger slug cropped from the previous photo shows the head part on the left. The slug has its genital pore on the right side of the body so the genital pore is down on the photo:
Phyllidia flava laying eggsPhyllidia flava starts the laying in the center of the spiral, of course. But some species are known to start the spiral ribbon from the outside.(!) Most nudibranchs lays the spiral ribbon in an anticlockwise direction. There are very few nudibranchs that lays egg ribbons in a clockwise direction. Phyllidia flava lays eggs in the same way as the majority of nudibranchs in an anticlockwise direction. You are seeing an underside of the egg ribbon through the transparent glass of the aquarium so the ribbon appear clockwise on these three photos.

Two egg ribbons of Phyllidia flava from underside:
Phyllidia flava egg ribbonsReferences

Rudman, W. B., 2004 (August 2) Nudibranch egg masses – the direction they spiral. Sea Slug Forum. Australian Museum, Sydney.

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Photo of the day (71): Phyllidia flava

Phyllidia flava is a species of a sea slug living in Mediterranean Sea. It lives and feeds on an Axinella cannabina sponge and on other sponges.

Phyllidia flavaThere are two Phyllidia flava slugs on the photo. The left one is emitting some chemicals as a self defensive behavior against predators. This is one of various ways of self defensive behavior, that sea slugs use. I did not hurt the slug anyhow. I just moved it from one aquarium to an aquarium for taking photos and the slug felt threatened. There is an Axinella cannabina sponge on the photo in the background too. My slugs comes from Croatia.

It did not emit the “smoke” for a long time. The slug looked after 72 seconds like this. You can also see gills between the foot and the mantle.
Phyllidia flavaReferences

Kirkland I. (2017) Self Defense. Last change June 9, 2017. Accessed March 15, 2018.