The study describes the unusual reproductive strategy of the species Antarctonemertes riesgoae. Image: Sergi Taboada, UB
Brooding is a usual behaviour in animals. However, to observe it in a marine worm is exceptional and, more surprisingly, it guards eggs from external threats. The scientific finding, published recently in the journal Polar Biology, was developed by researchers Conxita Àvila and Sergio Taboada, from the Department of Animal Biology of the University of Barcelona (UB) and members of the Institute of Research in Biodiversity (IRBio); Juan Junoy, from the University of Alcalá; Javier Cristobo, from the Spanish Institute of Oceanography, and Gonzalo Giribet and Sónia Andrade, from the Harvard Univesity, among other experts.
Nemerteans are a group of invertebrates mainly found in marine waters. The research group led by Professor Àvila, who coordinates the project Actiquim developed in Antarctica, discovered a new species of nemerteans, Antarctonemertes riesgoae, which has a reproductive strategy unique in this group: it broods like hens.
In marine Antarctic waters, UB experts found some 2-3 cm long cocoons brooded by female nemerteans. During reproduction, females secrete a very dense mucous through the body wall; it solidifies when getting in touch with marine water until creating then an elastic layer. Once the cocoon is created, females lay eggs on it. Unexpectedly, they act in a non-passive way: when cocoons are disturbed, females show a defensive behaviour and go out through cocoons’ openings.
Generally, nemerteans, like other living beings, lay eggs but later they do not brood them. To date, only two nemertean species were known to brood eggs. According to the research group, this exceptional behaviour is due to extreme Antarctic weather conditions. The strategy may result in an increase of reproductive success for many Antarctic species which can only reproduce themselves during the polar summer.
It is important to remember that the group led by Professor Conxita Àvila participated in the discovery of a new species of Osedax, a bone-eating marine invertebrate, named Osedax deceptionensis. This species, together with the so-called Osedax antarcticus, are the two first species of this type of marine worm found in Antarctica. Professor Conxita Àvila has coordinated the project Actiquim (I and II) since its setting up in 2007. The project is funded by the former Spanish Ministry of Science and Innovation. Its main objective is to analyse chemical ecology in marine invertebrates which inhabit Antarctic waters.