Fish blood as a chemical signal for Antarctic marine invertebrates

Chemical cues released from dead or injured organisms constitute important signals informing nearby animals about a feeding possibility. The ability to detect the signal, evaluate its meaning and locate its source can help organisms to exploit food resources efficiently, which is especially important to animals living in environments with limited food supply. Experiments were carried out to study the behavioral responses of several Antarctic benthic invertebrates to fish (Notothenia corriceps) blood. Necrophagous species such as sea stars Odontaster validus and Lysasterias sp., amphipod Waldeckia obesa and nemertean Parborlasia corrugatus responded to fish blood with changes in their behavior. The behavior common to all these species was locomotion directed towards the stimulus source. Behavioral components consistent with food consumption were observed in O. validus and P. corrugatus. The reaction of herbivorous limpets Nacella concinna to fish blood depended on the animal size. Large (>10 mm) limpets showed no behavioral response, whereas small ones (<10 mm) reacted to the stimulus by moving a short distance away. These results indicate that blood released from the tissues of injured or dead animals may be an important chemical signal for organisms belonging to different taxa.