Bonellia (Bonellia viridis Rolando, 1821) is a marine invertebrate of the Bonellidi family that lives, among other things, in the shallow waters of the Mediterranean. His marked sexual dimorphism is remarkable. Bonellia viridis Bonellidi Mediterraneo intotheblue.it
Morphological aspects The female of bonellia is green, the body is formed from an oval part (about 6 ~ 8 cm long) and a long proboscis (up to a meter long) which at the end divides into two (assuming the characteristic “Y” shape).
The male instead remains in a larval state (even if sexually mature) from 1 to 3 mm in length and spends the whole life cycle inside the female in a sort of symbiosis (in reality the term symbiosis is defined for organisms of different species , therefore not applicable to this case). It has a “simplified” morphological structure: the digestive system is very small (living inside the female, absorbing the nutrients through the epidermis), and there is no circulatory system, most of the body is occupied by the organs of reproduction.
The bonellina The female secretes a green pigment, the bonellina, which allows her to paralyze the small animals that are then eaten. In the presence of light the bonellina induces the interruption of mitosis and the “breakup” of other cellular apparatuses, thus killing bacteria, larvae and other small organisms. Due to these biocidal properties it is currently studied as a possible substitute for antibiotics.
Distribution and habitat The species is widespread in the Mediterranean, in the Red Sea, in the Atlantic Ocean of the northeast and in the Indian Ocean and in the Pacific. It lives in the depths between 10 and 100 meters deep.
Biology Food and Nutrition The female is a saprophyte and feeds, through the proboscis, of small organic debris and small animals that it finds on the seabed. The male, as mentioned, feeds on the food introduced into the female’s body.
Reproduction The female produces the eggs that are fertilized directly by the male that lives inside it.