Georgina Jones is a Senior Naturalist of the Southern Underwater Research Group (SURG). For almost 20 years, Georgina has been a passionate scuba diver with a lasting and ever-increasing passion for the underwater life of False Bay and the Cape Peninsula. Georgina has published several well-respected resources used by divers and marine scientists to identify species found below the waves, and has made some of her own new discoveries along the way. We can think of few people with as much first-hand experience with South Africa's underwater ocean heritage, and are pleased to share her insight into the unique parenting styles of our marine animals.
Heritage. To human beings, it can mean the smell of a recipe that your great aunt always made, an annual festival, a particular pen. But what about heritage in the marine world? In what ways do marine animals pass on benefits to their offspring?
Like human parents, heritage varies between families - from the casual to the lavish.
In some marine snails, it's all about the firstborn. Woven whelks' developing embryos are laid in egg cases that contain many eggs, and from there it's a race between the eggs in the case as to which develops first. The first to develop will then eat all the other eggs, eggs that were essentially provided by the mother for her eldest's nourishment.
In the shysharks, the mother lays an elegant egg case called a mermaid's purse and this otherworldly capsule contains a yolk to feed the growing baby until it bites its way out of the case.
While shyshark egg cases are smooth and translucent and rather prone to attack by predatory snails and other animals interested in eggs for breakfast, skates make their egg cases considerably tougher, with a dense webbing-like texture, and although they are left on the sand by the mother, they are equipped with anchor hooks to hold them in place while the baby inside grows.
Sea slugs lay eggs in ribbons and rosettes and also leave the developing embryos to their own devices, but the parents do provide some heritage for their offspring. One is poison: the eggs are spiked with toxins as they are laid in an attempt to deter predation. In many cases, this works, but there are specialist predators which not only eat the eggs, but also take those carefully provided poisons for their own protection.
The other is quite simple: making sure the babies emerge right at their preferred food source.
Male sea spiders go a bit further and carry their partners' eggs around with them while the babies develop. These males will even keep their offspring with them once they've hatched. They have an extra set of legs especially for this purpose, which the females of many species of sea spiders lack.
Furred sponge crabs
Furred sponge crabs literally give their babies the cloaks off their backs. Sponge crabs are part of the porter crab family and have a specialised pair of legs that holds a sponge or other animal on their backs, presumably for protection. In the furred sponge crabs, the parent broods the developing babies and once the babies have hatched, they make their way onto the parent's cloak, acquire themselves some of the cloak, and set off into the ocean leaving the parent's cloak to heal as best it can. Since the parental cloak is made from a living animal, regeneration and healing is possible.
Heritage, as in the human world, can mean many different things in the marine world. But one thing is certain - whether you're a sea slug or a South African, ocean heritage affects us all!
If you'd like to learn more about our ocean heritage this Heritage Month - be sure to sign up for our weekly #OceanHeritage newsletter!