Volume 1: Sea Urchins (Julian Fell)

Additional posts on the Echinoderm-L Listserv has led to a few more 'general' Echinoderm World Records. Thanks to Ben Wigham, Yannick Dewael, Alexander Kerr,  Jean-Pierre Feral and others who contributed to the thread!

 (Note: This page is image dense and may take a moment to load depending on your download speed. Additionally, many of the pictures on this page are "rollovers." Try placing your mouse over some images to see a different view! Links on images are to NMNH specimen labels.  Except where otherwise noted, images are of NMNH specimens, taken by S. Hottenrott)

Trivia: Maureen Downey described an echinoderm that has a bona-fide entry in the Guinness Book of World Records: the sea star Midgardia xandaros.



Largest Sea Star: Evasterias echinosoma 96 cm (37.79 inches) in diameter, weight 5 kg (11 pounds), collected in the North Pacific



Smallest Sea Star: Leptychaster propinquus 1.83 cm (0.72 inches) total diameter (at left, another small star: Asterina wega, USNM 6208)


Deepest Sea Star: Eremicaster tenebrarius collected in 7,630 meters (25,032 feet) (shown is USNM E9665 collected at 4,074m)


Fastest Sea Star: Sun Star, Pycnopodia helianthoides 75 cm per minute (0.027 miles per hour)(shown is USNM 1226)



Largest Sea Urchin: Sperosoma giganteum Test diameter of 38 cm (13 inches) (see "Urchin Records" below).


Smallest Sea Urchin: Echinocyamus scaber Test diameter of 5.5 mm (0.21 inches) (shown is USNM E36092)



Deepest Sea Urchin: Unidentified specimen taken from 7,250 meters (23,786 feet) near Indonesia in 1951 (see "Urchin Records" below).


Largest Sea Cucumber: Members of the genus Stichopus have been measured up to 1.3 meters (40 inches) in length and 20 cm (8 inches) in diameter:

Contributed by Alexander M. Kerr

    The longest holothurian that I know of is Synapta maculata.  It is often reported in the literature as being around 2 m, as are at least a couple of other synaptid species.  I have seen a specimen of S. maculata on Guam that was 3.3 m.  Bob Richmond of the University of Guam Marine Lab has a photo record of another specimen over 3 m in length.  While on the Great Barrier Reef Expedition, CM Yonge reported an S. maculata as 5 m.  All subsequent reports of 5m Synapta as far as I can tell can be traced back to this account.  In 10 yr of diving and collecting holothurians in the Indo Pacific I have never seen, nor heard even an unreliable report of, a specimen that long.  I suspect that the author did as I have sometimes done: mistaken two specimens for one when they're entangled in such a way that they appear to be a single, Goliath animal. (shown is USNM E35388, Synapta maculata)


Thelenota anax, a stichopodid, is another big Indo Pac cuke (its relative, Thelenota ananas, is shown at left).  While considerably shorter than S. maculata at just over a meter, it is the most massive holothurian, weighing in at a max of about 5 kg drained wet weight. The three other known congeners (including an undescribed sp.), are somewhat smaller at just over 2 kg.  The coelom of Thelenota is truly spacious; I've several times dissected specimens hosting three 20cm specimens of an inquiline carapodid fish!


Deepest Sea Cucumber: Unidentified specimen taken from the Philippine trench in 1951 in 10,190 meters (33,431 feet)

Smallest Sea Cucumber: Rhabdomolgus ruber, found in the North Sea 10 mm (0.39 inches) in length (at left is another small cucumber, Psolus punctatus, USNM E40643)

Largest Crinoid: Heliometra glacialis, found in the Northeast Pacific 90 cm (36 inches) in diameter




Smallest Crinoid: Unidentified species with a diameter of 3 cm (1.18 inches)





Deepest Crinoid: Unidentified specimen taken from the Kermadec Trench in 1951 in 8,210 meters (26,935 feet)


A recent exchange on the Echinoderm-L Listserve began with a question posed by Phil Lambert. What is the largest urchin? This resulted in a list, compiled by Julian Fell , of urchin 'records' notably absent from the most recent 'Guiness Book of  World Records.'

Contributed  by Julian Fell

Largest Urchins: There is no clear answer as it is entirely dependent on the criteria for  size that is used. I have arbitrarily set the following categories and provide the running leader in each one to the extent of my knowledge. A sort of Guinness Record for each one.

One thing I have noticed is that within each range of a species and within each range of a genus, the largest specimens or species are to be found in the range that is at the highest latitude, ie furthest from the equator. Bermuda has the largest specimens of West Indian species. New Zealand has the largest South Pacific  forms. Any other observations along this line? Record submissions should include localities.




Largest test diameter: The winner here goes to the Echinothuriids, Hygrosoma hoplacantha 280 mm and Sperosoma giganteum 320 mm. These are Deep-water soft/flexible shelled animals that have a low profile like an inverted soup plate. They collapse flat like pita bread when removed from the sea, but this does not increase the diameter, it only wrinkles the aboral surface. There is a Palaeozoic Fourierechinus 350mm and Proterocidaris 300 mm. Top image: Araeosoma belli courtesy of David Pawson. Bottom image:  Hygrosoma petersi.


Greatest mass (dry weight): Possibly Heterocentrotus trigonarius (left) with its massive spines but a Phyllacanthus (cidarid) is also a possible candidate (rollover image).



Largest test by volume: Possibly an echinothuriid again but I would suspect a Euechinoid.  Candidates would include: Echinus esculentus (right, rollover image) 176mm (but 200 mm reported), Echinus melo 145 mm, Evechinus chloroticus (someone reported 186 mm), Sphaerechinus 160 mm, Toxopneustes 150 mm, Tripneustes ventricosus 150 mm but fossil Tr. proavia 170 mm, Strongylocentrotus franscicanus (left) 160 mm with spine spread to 300 mm, and Astropyga 180 mm.


Largest test height: Easy. Dermechinus horridus. The height can be three times the diameter. Height over 130 mm known.


Largest spine tip to spine tip diameter: This is really tricky, sort of like antlers on an Ungulate,  the widest spread does not automatically come from the largest  animal.  I would give the prize to one of the Diademas. The largest  mention of size is 3-400mm, but It is not clear whether this is spines or spread. The longest  spine otherwise is 250 mm which gives a potential spread of near 500 mm. The largest test with these would be around 100 mm. There  is a sneaky possibility that an Aspidodiademid could take the prize.  These deepwater beasties have very small tests, 15-30 mm, but spines  up to ?20cm. Total spread over 35 cm possible. Other possibilities  include some cidarids that have very wide spread and Heterocentrotus (slate pencil) which cheats by having an oval test. Image of Aspidiadema jacobyi courtesy of David Pawson.


The proportionally largest spread category for longest spine as ratio of test diameter would go to a Saleniid, where 10:1 is possible. Other possibles include some cidarids that have very wide spread (Histocidaris To 340 cm). Image of Histocidaris sharreri courtesy of David Pawson.



Irregular  Urchins

Largest test diameter: Clypeaster latissimus 235  x 190 and Cl. Euclastus 184 x 190.

Greatest long axis: Plagiobrissus grandis. But there are some very large Clypeasterids. (rollover image)

Largest test volume: Plagiobrissus grandis (above) 220 x 165 x 55, Meoma vetricosa (left) 188x158x100, Brissus gigas 185x167x90, Spatangus thor 134x121x78. (rollover image)

Largest mass: Very difficult because irregulars include guts full of sand. Excluding sand it could be one of the beasties listed in largest volume (above) but Clypeaster rosaceus (right) is my nominee. There are no weight data on echinoids. (rollover image)

Largest spread (spine to spine): Some brissids and spatangids have long dorsal primaries which if spread sideways or forwards could achieve considerable span, but they are normally pointed backwards only so this category is probably not an appropriate one for irregulars. (photo of Plagiobrissus courtesy of David Pawson)





Oddest  shaped test: Pourtalesia, Echinosigra, Rotula,  (and some fossil forms). Pourtalesia laguncula (right), Echinocrepis rostrata (left), Rotula augusti (above) and Rotula obicularis (below) (rollover images)





Distributional  Records

Furthest North: intertidally Strongylocentrotus droebachiensis, but a single deeper water candidate has not been identified (there are  several candidates) (rollover image)



Furthest South: Sterechinus neumayeri, intertidal from McMurdo Sound (Ross Sea) or Vahsel Bay (Weddell Sea) (rollover image)


Greatest depth: Pourtalesia heptneri 7340 m.




And the fastest: I would propose an echonothuriid. Some of these puppies really motor-swim-bounce-skim over the bottom, but I have heard accounts of Astropyga's (tropical diadematid) having similar speed. These "walk" on spines on level sediment rather than move using tubefeet.  (Astropyga, right, rollover image).