|Photo by Matt Kiefer via Wikipedia:
Today's post is a kind of response to a fairly common request I get via email: "Can you help me ID this species of starfish from the Philippines?" (paraphrased)
A question I get from divers, photographers and students who actually live in the Philippines. And strangely enough I get it quite frequently and there are surprisingly few resources to help people with pictures.
In the past I have done variations on this by crowd sourcing images off places like Flickr and YouTube and its been awhile since I've done an "on line field guide." So I thought it would be a good time for another one!
With the exception of Acanthaster brevispinus (above), EVERYTHING below is taken from Flickr and recorded as being from the Philippines by the photographer.
The Philippines has a rich, RICH diversity of sea stars (as well as many, other marine animals) and so this "guide" won't be complete, but it includes several of the most frequently encountered species which are photographed and put on the web.
If you are looking for professional taxonomic monography of Philippine sea stars a good place to start is the work of Walter K. Fisher at the Biodiversity Heritage Library. HERE.
There are many, MANY published ID guides to the Indo-Pacific area and I've identified species in many of those books. But these days, images of sea stars and other marine animals are so prolific, it became clear that it really wouldn't take much to curate a collection of these to provide help for people who want to know what the animals were who didn't have expertise to the published accounts..
Another place to look for a nice crowd-sourced inventory of sea stars from the Philippines or anywhere is at iNaturalist! Go HERE. Identifications are not always from experts but its a good place to start.
I always like to remind folks when actually in the field.. look but don't TOUCH (or at least put it back!)
So here we go in reverse alphabetical order....
Euretaster attenuatus. This species belongs to the family of sea stars which are best known as "slime stars" in cold-water habitats. There's only been one account of the tropical species using "slime" as a defense and it wasn't really in a scientific journal.
This species has a distinct hole in the center of the disk called an osculum which allows water into the surface of the disk which is kind of like a circus tent that covers over the ACTUAL surface of the animal underneath (see the blog link above).
Its a species we know very little about. Another species, Euretaster insignis is usually what gets encountered in the Philippines. This image however most resembles E. attenuatus which was first described from New Caledonia. This is possibly a new record!
This species occurs widely around the Indo-Pacific, extending into the Indian Ocean with many, MANY color variations. Food, biology, etc. are poorly known.
As I've written about before here, this is one of the most heavily fished sea stars in the Indo-Pacific. Not just for tourist baubles but also for the aquarium trade. Its a handsome species and frequently gets "volunteered" for tourist pictures, beach moments, and aquarium scenes.
Nardoa frianti The genus Nardoa is named for the Italian naturalist Giovanni Nardo as I discussed in a post WAAAY back in 2008
There are MANY species. And they are often quite complicated. Even this one with its distinctive tubercles (the bumps) is conceivably part of a broader species complex. To make things even more complicated, you will sometimes see Nardoa species with these big bumps in the genus Gomophia.
Nardoa sp. similar to "N. novaecaledoniae" This one has flattened or at least, MORE flat plates relative to Nardoa frianti (above).
The exact species ID for this animal can't be made from a picture like this because we need to see the underside in order for the precise details. It LOOKS like a species that I would call Nardoa novaecaledoniae but there are several other possibilities. Close up on the underside would be necessary.
They have relatively solid surfaces with spiny surfaces. There is relatively little known about their general biology.
Luidiidae. There's only one genus in this family, Luidia and I've written about the general biology of the group here. The genus named after Edward Lhuyd, a Welsh naturalist.
Most members of Luidia are 5 armed..but for whatever reason, the ones in the tropics are often BIG and have more than 10 arms!
Luidia avicularia?Interesting to see this one since it doesn't usually occur at shallow depths. But the color pattern matches.
Luidia maculata This is a fairly large predatory starfish, often found buried below the surface of the sand.
We know very little about it.
Echinaster callosus I've seen this species often mixed up with Nardoa frianti, above. The big difference is in the texture of the "puffy" structures on the surface. Nardoa's bumps are just that- hard bumps covered by granules.
The surface of Echinaster callosus is covered by a bunch of big colorful puffy pin cushions. The big blobs are soft and each surround a sharp spine. When dead, they often deflate.
Colors are quite pretty and variable...
This species appears, at first to be fairly non-descript but a lot of things are going on with this species. In addition to the asexual reproduction and arm regeneration, this species is also often the host to benthic comb jellies! You can read more about that here.
Acanthaster planci (or A. cf. solaris). The notorious Crown of Thorns starfish has recently been studied using molecular techniques and revealed to actually be SEVERAL species. The one occurring in the Pacific has been referred to an older name, Acanthaster solaris. But presumably there are still several details to work out..