Snails that eat Starfish! Predation in the tropical Indo-Pacific!

In cold and temperate water habitats, starfish, especially asteriid starfish are often predatory. ESPECIALLY on mollusks! Famously on bivalves and clams but also quite a few gastropods aka snails.

But in the tropics, we often find the tables are turned! Snails, especialy giant snails, such as these Giant Tritons (Charonia sp.) are big, ol' meanie predators on several often, equally large and heavily armored (or at least well-defended) starfish species...


The Triton Vs. Crown of Thorns (Acanthaster planci) 
Just walked out of Godzilla and want to see two big monsters fight it out?? You've come to the right place!

The "Triton's Trumpet" is a large snail with a shell that is often up to two feet long. Because it is large and showy, it is often sought after as a souvenir.   Here we have not one but TWO videos of these giant snails attacking the very spiny Crown of Thorns starfish, a voraceous predator of corals





When the snails get to work, they often appear to be successful. But even if not, with the crown-of-thorns starfish there's *literally* many more fish (or starfish) in the sea!

this did not end well for the starfish.


The Triton vs. the "Blue Linckia" aka Linckia laevigata
Here..what you are seeing is NOT a hermit crab, but one of these giant triton snails finishing off its dinner, a blue Linckia laevigata, eating it disk first with the legs sticking out of the shell's opening..


Here's what this looks like with a bit more perspective...

The Triton vs. the Cushion Star (Culcita novaeguineae)
Another target species?  The big, round, almost pillow shaped starfish Culcita novaeguineae!

A pic to give you some perspective...


Other Indo-Pacific species include Choriaster granulatus 

Nardoa novaecaledoniae (Ophidiasteridae)


And in the Atlantic Caribbean (Cozumel), this "triton" snail attacking the tropical Oreaster reticulatus.  Honestly, I'm not sure if I've ever heard of this.. maybe something new? Will have to check...

Attacking a small specimen of Oreaster.. maybe O. clavatus?

via Wikipedia from NOAA photo library

And of course, its not always, the BIG snails.. the tiny ones can be predatory as well.. Here are individuals of Phos nodicostatum (Buccinidae) feeding on the arm of a crown of thorns..



NEXT UP! Pt. 2 to this.. SNAIL PARASITES!! 

The Cushion star Culcita novaeguineae: An exercise in growth-related taxonomic confusion!

So, people have seen some of the high-profile accounts of how some weird deep-sea fish classified into three families, were actually shown to be the males, females, and larvae of one species!
Well, not to be outdone, we at the Echinoblog have a similar (if somewhat less extreme) version of that...

Ontogeny and growth of course can be quite a pickle of a problem when trying to understand the diversity within a species.

For example, here is the juvenile form of one individual.
And here is the adult!! They look NOTHING alike!!
Now, if we look at Culcita novaeguineae, a starfish which inhabits the tropical Indo-Pacific region where it feeds primarily on coral .
We have a parallel where the JUVENILE is VASTLY different from the ADULT!!

Can you possibly believe that THIS?

(from the TideChaser: a blog about marine life from Singapore!)

Is the juvenile form of THIS????

(from the TideChaser: a blog about marine life from Singapore!)

I actually get a whole bunch of images from curious aquarists, divers and even scientists who have seen the big cushion stars and the tinier, "cookie" stars but NEVER realized that they were the SAME!!

How does that happen?
As it turns out, this species..as well as all species within the OREASTERIDAE have this particular developmental quirk.. That is there is what's called a "goniasterid" phase. the babies look like members of a different FAMILY!!
The small "cookies" were called "Goniodiscus sebae" (among about 12 other synonyms) and were members of the Goniasteridae until they were "raised out" to the adult forms.

(Goniasteridae: Peltaster placenta for comparison)

Whereas the adults were called Culcita novaeguineae and were members of the Oreasteridae.

and what happens? Quite simply, they just grow out, becoming more "inflated" as they reach an "adult" size, making cushions out of cookies!!

(from the TideChaser: a blog about marine life from Singapore!)

As it turns out, MANY members of the Oreasteridae have a "juvenile stage" and this complicates our understanding of just how many prominent oreasterids are the older, bigger stages of smaller cookie-or otherwise tiny starfish in other groups?