The most fascinating and colourful creature on earth has to be the nudibranchs or sea slugs. Always fascinated by the array of colour combination they demonstrate and the ability to camouflage. Almost a new species is found everyday. Up till now there are more than 3000 species known to human. Sorry for those who misread the title of this post, but this is a perfectly healthy page dedicated to the marine animals. Come on…
Nudibranchs or sea slugs represent fascinating and colourful life form. Their name is pronounced nudi - brank and it means "naked gill". As the name suggests the vast majority have gills outside their body and they have evolved without the protection of a shell. In all nudibranchs the shell is only present in the larval stage. As adults, the mantle replaces the shell.
They can be found throughout the world's oceans at all depths. The only place you will not find them are high energy areas, such as heavy surf close inshore where their soft body could be damaged.
Anatomy of Nudibranch
The mantle.
The surface of the mantle may bear tubercles which vary in size, shape and number and are often a character used to identify nudibranchs. Acid glands and/or spicules are incorporated in the mantle tissue and it is thought that these are mainly defensive in function.
Processes found in some species have coloured tips and contain defensive glands and have been shown to produce chemicals distateful to fish.
Cerata
The cerata contain branches of digestive gland.
The rhinophores.
The head region of nudibranchs bears a pair of sensory tentacles called rhinophores. These structures are primarily chemosensory (smell, taste) in function. In many dorid nudibranchs the rhinophores can be retracted into a basal sheath. The shape of the rhinophores varies greatly from one species to another and a table showing the different types of rhinophore found in British nudibranchs is provided to help identification.
The gills.
In nudibranchs the gills are probably the most important respiratory organ, however gaseous exchange also occurs over the entire body surface. In dorids the gills consist of several feather-like structures that encircle the anus. The gills can be retracted into a gill-pocket.
The oral tentacles.
Many nudibranch species have a pair of processes, one on either side of the mouth, which are probably involved in identifying food by taste or touch.
Feeding
Nudibranchs feed on other invertebrates such as sponges, soft corals,
anemones, sea pens,
Portuguese man-of-wars and hydroids.
Certain species are specific about their diet and feed only on a single or small selection of hosts, others are generalised browsers.
Certain species eat the eggs of other nudibranchs. These tend to be pale in colour so that they can go unnoticed on the egg masses. Sneaky!
Defence
Nudibranchs have an amazing array of defences. Colour is believed to be an important defence in many species. Others ingest and utilise the stinging cells from soft corals.
Particular species bury themselves in the sand and others hide during the day coming out at night.
They do not have shell for protection, but they use highly sophisticated chemical warfare. When distressed, some species secrete toxins so deadly that it could kill marine animals within 50cm radius.
They obtain this toxin from their food source containing chemical compounds which they store. Some species accumulate the poison in their Cerata, tentacle type sacks located along their backs away from their head, others store in the dorsal body wall.
The striking colour is for camouflage and as a warning to predators not to eat them because they are poisonous or pretending to be.
They travel by producing slimey mucus and using muscle or hair movement on the fleshy foot.
Reproduction
They are hermaphroditic possessing both male and female reproductive systems. Their gonad is located on the right side of their body close to the head as shown below.
Each nudibranch is both male and female producing sperm and eggs. To mate, two nudibranchs come together side by side and pass sperm sacs through a tube in their 'neck' to each other as shown in picture below.
Both then go their own way and lay egg masses that may contain millions of eggs.
The egg mass, which in most cases is laid in an anticlockwise spiral is made up of thousands of small eggs giving a speckled appearance.
Nudibranchs life span vary from 4-5 weeks to one year.
Spoil yourself with the beautiful colours of nudibranchs!
Spanish Dancer
One of my favourite nudibranch is the Spanish dancer.
This is the largest species of nudibranch, which can grow to as much as two feet in length. This specimen is about a foot long. Spanish Dancers are often seen swimming through the water in peculiar movement which is fascinating for divers to watch, as they simultaneously bend their body up and down, and move the edges in a wavelike motion.
The Spanish dancer dances as the diver gazes…
They definitely have the nicer costume than the Spanish dancers I paid through my nose to watch them do the flamenco dance in Barcelona, Spain!
See what I mean? OL attire for Flamenco dance...
No offense to the dancer cause her flamenco dance was really skilled.
But I'd rather gaze at the spanish dancer nudibranchs as they grace through the water. =)
That is what makes our marine lives so precious.
I would like to dedicate this post to my friends who are troubled with unhappy things in their lives at the moment. Hope that you will be strong in this difficult phase of your life and paint your life with beautiful colours of joy and happiness once again. God bless you.
May your life be as colourful as the living colour of the ocean, nudibranchs. Love you all.
Love the Ocean. Protect the Ocean.
Please leave comments and thoughts in the chatbox at bottom of page. Thank you.
For more information, visit :
May your life be as colourful as the living colour of the ocean, nudibranchs. Love you all.
Love the Ocean. Protect the Ocean.
Please leave comments and thoughts in the chatbox at bottom of page. Thank you.
For more information, visit :
http://www.seaslug.org.uk/nudibranchs/anatomy.html
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