Sea Slugs | The Nudibranchs | The most Beautiful Molluscs

 

These are the most beautiful, cute and diverse group of animals, with over 2000 species. They go by  the common name "Sea Slugs".

Sea slugs are closely related to snails except for the fact that they are marine. Sea slugs are just marine and shell-less Snails.

** Berghia Coerulescens, is a beautiful and vividly coloured species of sea slug, a marine nudibranch in the family Aeolidiidae. Mostly seen in Atlantic ocean, Central and Western Mediterranean from Brittany coasts to Canary Islands. They grow to sizes ranging from 40mm to 70mm. **

** The (orange) horn like projections on the either top of the head are know as "Rhinopores", which are used to sense the surroundings (chemo - receptive, the same way our nose and tongue works) **

Sea slugs further come in many types :-

Aeolids

    They are the carnivorous slugs preying on Cnidarians !!

These slugs have special adaptations enabling them to harvest the stinging cells, nematocytes.

*A Nematocyte, the stinging cell found in Cnidarians. *

One of the most captivating species of the Aeolids is the " Glaucus atlanticus ".

** Glaucus atlanticus, a.k.a the " Blue Sea Dragon " or even "dragon slug", feeds on the portuguese man'o war jellyfish's tentacles. They have special adaptations to avoid the stinging cells injuring them.*

Aeolid slugs have special adaptations to prevent themselves being victim of the nematocysts, such as having a special epithelial tissue of cells, lining the surface of the buccal cavity and esophagus, which contain specialized Ovoid Discs called "Spindles". These have been known to neutralize the damage caused by nematocysts.

→ In a study published in the journal BMC Biology, researchers from the University of Vienna in Austria examined the interaction between spindles and nematocysts in aeolids. They found that the spindles were able to bind to the nematocysts and prevent them from firing. The researchers also found that the spindles were able to block the release of venom from the nematocysts.

→ These findings suggest that the spindles in aeolids provide an important layer of protection against the nematocysts of their prey. This allows the aeolids to safely feed on cnidarians and acquire their nematocysts for their own use.

They have developed a mind boggling strategy of using Nematocysts for their own needs. They collect the unmature nematocyte cells in their "Cerata", which is the finger like projections on it's dorsal side and grow them. When alarmed or harmed they eject these these cells trough their cerata on the victims. ( Duplicating the effect of a sting from a jellfish !!)

Cerata, are fleshy, tentacle-like protrusions that project from the back of their body. The cerata are covered in a thin layer of skin that contains blood vessels. This allows the cerata to absorb oxygen from the water. The cerata of some aeolid nudibranchs are brightly colored and patterned, which helps them to blend in with their surroundings. This can help them to avoid predators.

We hope that you enjoyed and learned something new today also help spread this blog encouraging us to write more and more simplified Zoology for you !!

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J. Maanavendra roy,
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