CRITTER CONFIDENTIAL Summer lovin !
It ’ s the turn of invertebrate romance to come under the spotlight this month , and Paul Naylor is your guide / voyeur
Cuttlefish are real stars of the show if you are lucky enough to see them and , while keeping your distance , they are too preoccupied to worry about your voyeurism . Males flashing vibrant patterns along their backs and arms to woo females and warn off rival males are a spectacular sight . Their eventual mating consists of the male grasping the female by her head and passing her a packet of sperm with a specially adapted arm .
The male typically stays with his partner from that point to when she has completed laying her eggs . His attentive behaviour serves to guarantee his paternity , because fertilisation of the eggs does not occur until right before they are laid . That egg laying is amazing to see in its own right , as the female carefully puffs away any silt from the seaweed or other structure before meticulously tying on each ‘ sea grape ’ with its own little strap to form a bunch .
By the time you read this a good deal of the action will be well underway but , a few years ago , I was fascinated to watch a female cuttlefish acting strangely in mid-July . She was searching around previously laid clusters of eggs and seemed to be inspecting them closely . A cephalopod scientist confirmed she would have been looking for a good place to lay her rather late eggs , and it was not that unusual for one to do this without a male attendant .
Courtship is presumably quite straightforward for those molluscan relatives of cuttlefish , the sea slugs .
They are all hermaphrodites , simultaneously male and female , so every encounter is a mating opportunity . Couples usually engage in reciprocal fertilisation , as it is charmingly known , so both will end up laying eggs . The white egg ribbons or strings of the smallest sea slugs are sometimes more obvious to us divers than their cryptic parents , so it ’ s well worth a closer look if the eggs are spotted . Sea hares can mate in pairs , but also in longer chains where
Cuttlefish couple , the female will shortly lay her eggs
18