March marches on, not much to say other than I wish that the weather would make up its mind between warm one day and freezing the next. Last week we buzzed through the life of the hyper-competent Brown Hawker Dragonfly. This week we slow things down to a snail’s pace, hope you guys enjoy.

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Issue #165 – Triton’s Trumpet

Kingdom – Animalia

Phylum – Mollusca

Class – Gastropoda

[Clade]* – Caenogastropoda

Family – Ranellidae

Genus – Charonia

Species – tritonis

* The Class Gastropoda is still going through a taxanomic shake-up, and as such the Family Ranellidae could be in any of the following clades; Caenogastropoda, Hypsogastropoda or Littorinimorpha

Related Species - The Triton’s Trumpet Snail is one of three species in the genus Charonia

Range - The Triton’s Trumpet Snail can be found in shallow water reefs across the Indian and Western Pacific Oceans, including the waters of the Red Sea

Trumpet of the Gods

The Triton’s Trumpet Snail is a large marine gastropod, whose shell can reach up to 2ft in length, making it one of the largest extant species of snail in the world. The large size coupled with easy access to the shell, led to this species being harvested for decorative purposes, and on occasion as use for musical instruments, with the Japanese horagai and the Maori putatara being just some of the examples of this (2). Living Triton’s move on single large foot and navigate their environments using scents and chemical cues picked up by the black and yellow striped tentacles flanking the animal’s mouth.

Like a number of other marine snails, the Triton’s Trumpet is an obligate carnivores. Unusually the species is an active predator, and feeds predominantly on other molluscs and starfish. Most notably the species is the only persistent predator of the Crown of Thorns Starfish (Acanthaster planci), despite the prey’s larger size and array of venomous spines and thick armour covering its entire body. Once the Triton has caught up to the prey, it grips the starfish with its foot before sawing through the Crown of Thorns armour with its radula, until it reaches the soft tissue inside. From there the snail injects its own paralytic venom and then consumes its prey’s innards at leisure.

Unlike many gastropods, Tritons have fixed genders and are not hermaphrodites. Additionally unlike many other marine molluscs, the fertilisation of the female’s eggs is internal. Once fertilized the female lays her eggs on the sand, their sticky shells adhering to the sand which acts as an ad-hoc camouflage against egg thieves. Eventually the eggs hatch into free swimming larvae that stay in the plankton for the next three months before developing shells and sinking back to the sea-floor (3).

Nature’s Most Wanted #10 - Crown of Thorns Starfish

The Crown of Thorns Starfish (Acanthaster planci) is a large starfish with an average leg span of a foot (although specimens of almost a meter in width have been recorded) found in the waters of the Western Pacific and Indian Oceans. The species is predominantly a predator of hard corrals, and in small numbers are beneficial to reef survival since they control the growth of fast growing corrals, allowing slower growing species to gain a foothold. Recently however, the population of Crown of Thorns has exploded, thus threatening both the corral they feed on and the other animals and plants that rely on the habitats they create.

While the reason of the population explosion is as of yet unknown, theories relating to the removal of the Crown of Thorns predators, aggregation theory and ties to temperature and surface run-off yet, with the exception of the former theory, none have enough scientific weight to be the main cause of these ‘starfish invasions’, and even the one viable theory doesn’t explain how the population has expanded so rapidly. What is known, is that a long term infestation of starfish can reduce a reef to rubble, and when human factors are put in alongside starfish damage, that 24% of the world’s coral reefs are in imminent threat of being lost within a decade (4).

Due to initial limited predation, the Crown of Thorn’s is too venomous for most species to eat, there is little to no immediate predatory pressures to large populations. Currently injections of Sodium Bisulphate directly into the starfish’s blood stream are used to cull large populations, but this process, despite being harmless to the rest of the reef ecosystem is very labour intensive. At current the Australian government is investing in a UUV (unmanned underwater vehicle) project called COTSBot to automate the process of culling starfish, which is currently going through a trial period to test its underwater navigation systems (5).

Bibliography

1 - www.arkive.org

2 - http://collections.tepapa.govt.nz/object/155366

3 - Nugranad J, Chantrapornslip S & Varapibal T (2000) Feeding and Spawning Behaviour of the Trumpet Triton Charonia tritonis in Captivity Phuket Marine Biological Centre Special Publication

4 - http://www.cabi.org/isc/datasheet/109203

5 - https://www.scientificamerican.com/article/a-starfish-killing-artificially-intelligent-robot-is-set-to-patrol-the-great-barrier-reef/

Picture References

1 - https://ferrebeekeeper.files.wordpress.com/2014/01/2013-05-09-at-08-07-17-l.jpg

2 - http://cdn2.arkive.org/media/B0/B0AF2D20-5C8B-471A-B52F-0A3033A1B999/Presentation.Large/Triton-snail-Charonia-tritonis-attacking-crown-of-thorns-starfish.jpg

3 - https://adlayasanimals.files.wordpress.com/2015/03/crown-of-thorns-starfish-phuket-big.jpg

4 - https://www.scientificamerican.com/sciam/assets/Image/scientificamerican0116-16-I1.jpg

Hmm, not sure what to say about this one, hopefully the Crown of Thorns (and irresponsible human actions) can be controlled for the sake of coral reefs everywhere. Next week we have a prime-number crunching request from @bella_blackstar, but until then make sure to critic, comment and suggest future issues as well as making sure you check past issues in Impurest’s Bestiary

Many Thanks

Impurest Cheese

Want more IGTA? For a sneaky starfish, click here to meet the Giant Green Brittle Star. Or for another snail with a taste for flesh, click here to see the cannibalistic Rosy Wolf Snail.