{"id":28738,"date":"2019-08-28T00:05:00","date_gmt":"2019-08-28T07:05:00","guid":{"rendered":"https:\/\/hakaimagazine.com\/?post_type=custom_news&p=28738"},"modified":"2019-08-27T17:03:55","modified_gmt":"2019-08-28T00:03:55","slug":"these-sea-slugs-dine-while-they-do-it","status":"publish","type":"custom_news","link":"https:\/\/hakaimagazine.com\/news\/these-sea-slugs-dine-while-they-do-it\/","title":{"rendered":"These Sea Slugs Dine While They Do It"},"content":{"rendered":"

Sea slugs have a reputation for bizarre sex. For one, they\u2019re hermaphrodites that penetrate each other at the same time. One species, post-coitus, amputates its own penis<\/a>. (Don\u2019t worry: it keeps two spares coiled up inside its body.) Despite knowing all this, Licia Sales, a zoologist at the University of S\u00e3o Paulo in Brazil, was still astonished when she discovered mating pairs of Phidiana lynceus<\/em><\/a> sea slugs ripping off and eating each other\u2019s fingerlike appendages, called cerata, during sex.<\/p>\n

\u201cAt first glance, I didn\u2019t understand if it was mating or agonistic behavior because the individuals were very aggressive,\u201d Sales says.<\/p>\n

Sales and her colleagues filmed five pairs of sea slugs under a microscope to get a close look at the behavior. They confirmed that the animals were trading sperm so mating was definitely part of the act. But they were also eating parts of each other. The scientists dissected the sea slugs, which are roughly 30 millimeters long, and counted the number of cerata that seven of them had swallowed. The mean number was 13<\/a>.<\/p>\n

The team isn\u2019t sure why the sea slugs exhibit this behavior. They suspect it\u2019s an example of traumatic mating, in which the attacker harms its partner to boost its own sperms\u2019 chances of fertilization\u2014a tactic that is also observed in other invertebrates. Male seed beetles, for example, have spikes on their penises<\/a> that pierce a female\u2019s reproductive tract making it less likely that she will couple with a rival in her injured state.<\/p>\n

Traumatic mating often involves genitals, though, which is not the case for these sea slugs. \u201cThe damage is extra-genital, so it would not involve sperm displacement,\u201d says Jos\u00e9 Eduardo Marian, a member of the team. Marian says harming non-genital body parts during sex is rare for hermaphrodites.<\/p>\n