What Are the World's LARGEST Starfish??

The other day, I was thinking of BIG stuff. and then, a bit later, I was thinking of STARFISH stuff. 

and then I thought of cake. (mmm..cake..)

And then I thought What about a BIG Starfish POST??!! A survey of all the world's LARGEST starfish!!! 

Criteria: Different groups were evaluated primarily in terms of overall diameter and volume/mass. Some species, such as the brisingid Midgardia xandaros have REALLY long arm spans (4.5 feet!-to be discussed in a future blog!) but are just very minimal otherwise.

So...what's with the bigness?? Size doesn't seem to be really constrained to any specific climate type area. You see them in both

1. Cold-Temperate water regions

2. And in the Tropics. But WHY?? Nutrients? Predator defense? Growth constraints? Hmm.....
And so..in order of what I believe to be a rough estimate of overall mass to size priority..... (11. Labidiaster annulatus gets honorable mention!)

10. The Oreasteridae Fisher 1911 (Order Valvatida) Here is a WHOLE family of starfishes whose primary features include having heavily calcified, BIG oversized bodies. Three included species below are listed separately.

Most occur in the tropical Indo-Pacific in relatively shallow-water (some individual species occur in deeper-water). Examples: Culcita novaeguineae Mueller & Troschel 1842,  Pentaceraster spp. Protoreaster nodosus (Linnaeus 1758)

9. Big Luidia species (Familly Luidiidae, Order Paxillosida)

(thanks to Jen Hammock, USARP for scale!)

Most species of Luidia are pretty small to medium sized. Luidia occurs mostly in tropical to temperate shallow-water habitats and live on sandy bottoms throughout the world. Mostly have an adult diameter of roughly 7-15 cm but in some exceptional cases, they get HUGE. Pictured above is the rarely encountered Luidia superba from the Galapagos. This is believed to be a normal adult size. About 1-2 feet across (30-60 cm). YOW. (but, again-poorly known...)

A few other species of Luidia also get big...such as this Luidia maculata from Singapore

8. Macroptychaster accrescens (Koehler 1920) (family Astropectinidae-Order Paxillosida)

(from the recent NIWA cruise to Antarctica)

A big animal that lives in mud-soft-sediment in the Southern Ocean/Antarctica and has pointed tube feet. Adult size for Macroptychaster is about 1-2 feet (30-60 cm). The body cavity is frequently swollen making it appear even bigger than it already is! This species falls into the category "About which, little is known.."

 7. Poraster superbus (Mobius 1859) (Family Oreasteridae, order Valvatida)
A big oreasterid from the Indian Ocean. Lives mostly in tropical-shallow waters. All the adults I've seen are big, 1-2 feet across. This species also falls into the category "About which, little is known.."

 6. Oreaster reticulatus (Linnaeus 1758) (Family Oreasteridae, Order Valvatida) Oreaster reticulatus lives in shall0w-water settings in the tropical Atlantic. Not as big as some, only about 1-2 feet across (a big one shown above), but these get THICK. Easily 6-9 inches thick along the disk! An animal that has been facing regional extinction due to an overzealous tourist trade. An increasing amount of information on this animal is becoming available..a microalgal film/scavenger/opportunist and sponge feeder with some foraging-feeding behavioral complexity. A blog on this animal awaits!

  5. Astrosarkus idipii Mah 2003 (Family Oreasteridae, Order Valvatida) A weird beast I described back in 2003. This was first discovered by the Coral Reef Research Foundation during a coral sub-reef expedition (aka the Twilight Zone Expedition) back in 1997. This species occurs mostly in deeper water and is, found throughout the Indo-Pacific.

Its about 1.5-2.0 feet across but about 4-5 inches THICK. Its also unusual in that its mostly decalcified and has the fleshy consistency of a pumpkin..Its overall volume makes it much more massive then say, Luidia. Another one in the "about which, little is known" category...(but I will blog about it too someday!)

4. Pisaster brevispinus (Stimpson 1857) (Family Asteriidae, Order Forcipulatida) I have written about the Giant Pink Starfish from the west coast of North America. The lesson here is that Pisaster brevispinus gets BIG. Especially under conditions where it can feed and GROW. Aquariums I've worked in or visited report that this species can reach OVER TWO FEET across (~60 cm!)

Here is a big specimen collected years ago-with a human for scale. 

(thanks to Mr. Timothy Coffer for his modelling expertise!)

4a. Acanthaster planci (Linnaeus 1758) (family Acanthasteridae, order Valvatida) A big starfish-and tied for 4th place, but sorry Wikipedia, NOT the second largest in the world. Typical sizes range in the 1-2 foot size range (30-60 cm) but with reports of some animals reaching slightly over 2 feet (70 cm). I've written about this infamous Indo-Pacific corallivore and will undoubtedly do so in the future!

3. Evasterias echinosoma Fisher 1926 (Family Asteriidae, Order Forcipulatida) I have only ever seen one or two specimens of this species of this size..but diameter is recorded at 37.79 inches (96 cm!) Making it over 3 FEET wide! This species occurs in Alaska and the Aleutians. Many are big..but not all are quite this large..

2. Pycnopodia helianthoides (Brandt 1835) (Family Asteriidae-Pycnopodiinae, Order Forcipulatida) A famously known species known only from the west coast of the North America. Under aquarium or ideal feeding conditions-this animal easily reaches 2 feet (or 80 cm) across but has been observed to surpass THREE feet in diameter. But thing is, its all mostly decalcified.

Mostly fleshy tissue and soft stuff. Big volume and diameter but not much to its size out of water.. Pycnopodia is a voracious predator of uh..well almost everything. There's plenty known about it which is why I'll talk about it more during another blog post.

1. Thromidia catalai Pope & Rowe 1977, Thromidia gigas Mortensen 1935 (Family Mithrodiidae, Order Valvatida)

(From Dave Lane on the Santo 2006 Expedition)

Most people don't realize that one of the biggest, most massive starfish in the world lives in the South Pacific and Indian Ocean primarily in deeper water settings.

 It weighs in here at #1 because of its overall bulk, which reaches over 13.2 pounds (SIX kilograms!-yes, even I am skeptical) but reaches a maximum span of a little over 2 feet (60-65 cm).

Sea Urchins make a LOT of NOISE when they EAT!!

(from Picasa-akunidive)

I think that perhaps because of the North American Echinoderm Conference in full swing that the news is chock full o' echinoderm news this week!

Sea Urchins are apparently 'cacophonous' eaters!!

with the scientific citation here.

Craig Radford & associates at the Leigh Marine Lab in Auckland, New Zealand have found that the New Zealand sea urchin Evechinus chloroticus apparently creates LOUD FEEDING NOISES in the 800-2800 Hz range.

Timing of this increase in noisiness coincides with feeding habits of the sea urchin.

Apparently the test acts as a Helmholtz Resonator which, according to Wikipedia is described thusly:

When air is forced into a cavity, the pressure inside increases. Once the external force that forces the air into the cavity disappears, the higher-pressure air inside will flow out. However, this surge of air flowing out will tend to over-compensate, due to the inertia of the air in the neck, and the cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. This process repeats with the magnitude of the pressure changes decreasing each time.

which amplifies the ambient sound intensity in coastal waters by as much as TWO TO THREE ORDERS OF MAGNITUDE.

(resonator from Wikipedia)

Honestly. I never get tired of writing about echinoderms.

Hot & Cold News Round-Up

Echinoderm-related news is running hot and cold today......

1. Acanthaster planci: Fishing Bans Apparently Help Curtail Crown-Of-Thorns-Starfish Outbreaks (click here)

...New research suggests that fishing bans help control starfish outbreaks on the world's largest reef system.

Hugh Sweatman, of the Australian Institute of Marine Science in Townsville, Australia, used surveys of crown-of-thorns starfish on the Great Barrier Reef and overlaid them with the locations of no-fish zones.

Exactly how fishing bans reduce these outbreaks is not clear. Evidence that the protected fish control the starfish directly by eating them is scant, Sweatman said.

ore likely, he suggests, is that protecting fish causes a trickle-down effect.

Increasing populations of predatory fish reduce the numbers of bottom-dwelling fish such as wrasses, which eat invertebrates on the reef such as shrimp and worms. With fewer wrasses, invertebrate populations can swell -- and these creatures may be eating juvenile crown-of-thorns starfish and keeping outbreaks in check, Sweatman said.

2. Antarctic Biodiversity Suffers from Scouring Icebergs!

ScienceDaily (July 18, 2008) — Antarctic worms, sea spiders, urchins and other marine creatures living in near-shore shallow habitats are regularly pounded by icebergs. New data suggests this environment along the Antarctic Peninsula is going to get hit more frequently. This is due to an increase in the number of icebergs scouring the seabed as a result of shrinking winter sea ice. (original article here)

Tremaster mirabilis-"About which, little is known...."

You know what is frustrating about working on deep-sea echinoderms? You might have hundreds of specimens of some species..but you look it up to see if there's any BIOLOGY known (as opposed to systematics or taxonomy) ..and you get "The biology of this animal remains poorly understood..."

Case in point:Tremaster mirabilis

Taxonomy: Valvatida; Asterinidae; "Tremasterinae".

Where? South Pacific, Southern Ocean, North Atlantic, the Indian Ocean-pretty much all over the place but in deeper water! 300-500 m!

What else do we know? When alive, they are orange and appear to live with the lower "ledge" flush against the bottom. They are often collected in groups.

"Tremasterines" have what appears to be a Jurassic fossil occurrence...Apparently, a relatively old body form relative to other asterinids (if indeed they are truly related).

..... And there is a striking resemblance between Tremaster and a brain slug!!

Hubert Lyman Clark and other echinoderm biologists have apparently observed that Tremaster "incubates" its juveniles....but this behavior has never been thoroughly documented or examined...and "remains a topic ripe for study.."

What do those big interradial pores function for? Why the high conical body aspect?

And that's pretty much it. A summary (and the summary's dead-tree citation) of what's known about this animal is available here.

An intriguing and tantalizing beast!!

Plus...when observed from the oral surface, Tremaster bears a striking resemblance to the Sarlacc from Return of the Jedi!

Akelbaster novaecaledoniae: Weird Starfish of the Month

Its time for cool weird starfish stuff!

Some pics from a cool starfish I described a few years ago...
Akelbaster novaecaledoniae Mah 2007 (click to see citation).

Where from: Off the shelf of New Caledonia in the South Pacific 225-400 m.

Taxonomic Breakdown: Asteroidea; Valvatacea; Valvatida; GONIASTERIDAE; Pentagonasterinae (related to the Australian Tosia and the Australian-NZ Pentagonaster).

The Name: The genus "Akelb-" is an anagram of the surname "Blake" and is named for Dr. Daniel Blake at the University of Illinois, Urbana-Champaign in honor of his contributions to starfish paleontology and evolution.
The Starfish: Actually...a pretty small animal. But almost perfectly pentagonal. Only about 2-3 cm diameter but... Wow. One of those animals that just doesn't look natural...

The Weirdness Pt 1: This thing is COVERED by PEDICELLARIAE. Pedicellariae are little claw-like like structures that starfish use to interact with it surroundings (here is a general explanation). But HOW different pedicellariae function in this species is unknown.
Pedicellariae are present on each top-facing marginal plate and even on the dorsal (i.e., the top) facing plates. and then turn it over..and POOM!! There's THIS:
The pedicellariae also cover over almost ALL the ventral-facing plates. Each actinal plate with a complete bivalve pedicellariae!! What are all those little mouth-like pedicellariae things for?? I wish I could tell you.

The Weirdness pt. 2!! The strangeness continues!! When you turn the animal on its side and you can see these two little pits sitting at the junctures between the top (superomarginal) plate series and the bottom (inferomarginal) plate series.
Let's take a closer look at those pits....

Each one of those knobs looks like some crazy spiny horn gone crazy!

What do these do?
In the living animals these are covered by tissue and are pretty tiny..
Mini-current flow turbines? Filter feeding? Aracane Lovecraftian secrets hidden away amidst the armpits of goniasterid starfish? I don't knwo yet..but finding new species like this is often just the FIRST STEP in a cool new story..

Echinoderm Meetings Galore! NAEC, IEC! VIP-LOL!

FIRST! Excitement in Melbourne, FL at the NAEC!!
North American Echinoderm Conference (NAEC)

Where: Melbourne, Florida
When: July 20-25 2008
Who: Your Hosts-Richard Turner (Florida Institute of Technology) & Jim McClintock (U. of Alabama) with special Guest of Honor: John Lawrence
What: The NAEC is intended primarily for colleagues in Canada, the Caribbean region, Central America, Mexico, and the United States of America. It serves this geographic region between meetings of the International Echinoderm Conference, last held in August 2006 at University of New Hampshire.

Small meetings like this one is a great intimate setting for meeting the North American echinoderm scientific community. Especially for students. And in spite of the "North American" part of the name, past NAEC have entertained visitors from MANY continents!

THEN!! The 13th International Echinoderm Conference in Hobart, Tasmania!! January 5-9, 2009

Theme for the 13th IEC is: Echinoderms In a Changing World
Link here to see the site.

Important Dates

Abstracts due 15 Nov 2008
Early registration closes 15 Nov 2008
Registration closes 17 Dec 2008
In 2009 this Conference will be held at the University of Tasmania in Hobart, Tasmania (yes that's in Australia)-hosted by Craig Johnson.

Although deadlines remain months away..remember that January is a popular tourist time for that part of the world. Rumor has it that flights are already filling up! So, go get your reservation right now!!

Now, that is more echinoderm fun than you can shake a stick at.

P.S. to Craig-you need a catchy graphic for your conference!!

The 9th/10th Doctor's Desktop TARDIS setting should be URCHIN not coral!

Could this

(Histocidaridae from the NHM Echinoid Database)

be this? 

(from wikipedia-TARDIS)

And this...

(this is Aristotle's Lantern-the jaw in sea urchins)

Looks like this!

Thus, I can only conclude! 


Are the TARDIS roundels (the little pentagonal/round patterns) spine bosses?

By the Numbers... How MUCH is published on echinoderms???

So, while I was preparing text, budget numbers and accomplishments over the weekend in anticipation for my grant, I was inspired to do some "by-the-numbers" thinking about echinoderms and how much we know about them. Via publications.

I went to the Zoological Record database* (see disclaimer at bottom for search parameters) and looked at the classification of different "kinds" of research by echinoderm taxon.

I make no interpretations other than what seems apparent.

Here's what you get:

General Trends:

*Fossil publications recover the greatest number of hits for the Echinodermata, followed by development (thanks Strongylocentrotus!) and then systematics.

*Sea Urchin papers account for about 42% of the TOTAL number of echinoderm publications!! But of, those the majority of sea urchin publications are in development (so...mostly Strongylocentrotus).. None of the other remaining echinoderm groups really reaches this overall percentage of the total.

Asteroids make up about 18% of the total number of publications, breaking down with less. I'll be honest though, its entirely possible that crinoids (14%) are under represented in the ZR database. Crinoids occupy a prominent role in Geology as index fossils which may not be reflected in a zoological context.
Echinodermata (total=39,989 publications)

Name of Discipline # of hits
Fossils 7839 (note that x-ref with Paleontology only got 527 hits)
Development 7703
Systematics 6814
Ecology 6392
Physiology 3346
Morphology 3055
Genetics 2091
Taxonomy 1192

Class by Class Breakdown... (sorry-Living groups only...didn't get to do Paleozoic groups for now...)
Echinoidea (total=16,888 publications)
Fossils 3964
Development 4152
Systematics 2885
Ecology 2511
Physiology 1181
Morphology 1073
Genetics 1336
Taxonomy 355
Asteroidea (total=7,220 publications)
Fossils 700
Development 1114
Systematics 1373
Ecology 1481
Physiology 664
Morphology 676
Genetics 374
Taxonomy 218
Crinoidea (total=5,494 publications)
Fossils 3481
Development 337
Systematics 2247
Ecology 627
Physiology 127
Morphology 663
Genetics 88
Taxonomy 326
Holothuroidea (total=4,100 publications)
Fossils 326
Development 426
Systematics 1139
Ecology 603
Physiology 362
Morphology 446
Genetics 118
Taxonomy 232
Ophiuroidea (total=3,317 publications)
Fossils 550
Development 388
Systematics 1070
Ecology 644
Physiology 206
Morphology 376
Genetics 76
Taxonomy 169

*Their database extends back to 1864..but I think our access only extends to 1945. In any case, it doesn't make a significant difference-still a LOT of publications. Bear in mind..what you have is probably imperfect, biased and NOT at all as well-thought out as it probably ought to be, so any mistakes or logical errors are mine. (but if I worked all that stuff out-I would probably be submitting this for publication somewhere instead of doing this!)

Happy 4th of July! Brittle Star Video Mania!!

Ha! Its the 4th of July holiday and I'm writing grants and finishing starfish manuscripts..So, you guessed it! Its VIDEO TIME !! whoohoo!!

To paraphrase from 2001: A space odyssey: "Oh my god, its full of brittle stars (Ophiura?)"



Ophiothrix sp. fields off Anacapa Island (off the coast of California)


Ophiarachna incrassata I think? (from Bohol, the Philippines)


this isn't anything special-but how many times do you get to see Ophiolepis superba alive?