Class CUBOZOA Werner, 1973

Museums

Regional Maps

• Werner, B. 1984. Klasse Cubozoa. Lehrbuch der Speziellen Zoologie. H. E. Gruner. Stuttgart, Gustav Fischer Verlag. 2: 106-133. pp. 106–133 in Gruner, H.E. (ed). Lehrbuch der Speziellen Zoologie. Stuttgart : Gustav Fischer Verlag. [131, 132]
• Gershwin, L. 2005. Taxonomy and phylogeny of Australian Cubozoa. Unpublished PhD thesis. School of Marine Biology and Aquaculture, James Cook University, Townsville, QLD. 221 pp. 49 pls [102]

Introduction

The Cubozoa was long regarded as a minor order of the Scyphozoa, and it wasn't until 1973, when Werner and his colleagues published the life cycle of Tripedalia cystophora, that that began to change. They found that the polyps and the metamorphic process were entirely different than that known from the Scyphozoa, i.e., the polyps are truly radial and have a large nematocyst or cluster of nematocysts at each tentacle tip, and the polyp metamorphoses entirely into a juvenile cubozoan rather than strobilating off ephyrae. This, combined with earlier knowledge that the planula larva is unique in having eye spots, and the unique morphology of the medusae, drove Werner to elevate the group to the class level.

The Cubozoa has been widely embraced as a class based on morphology and developmental biology, and this hypothesis is supported by molecular studies. Although it is a minor group in terms of numerical species and generic diversity, some of the world's deadliest animals belong to the Cubozoa, making it a small but important group.

Perhaps the most intriguing feature of the Cubozoa is their eyes. All cubozoans have well developed eyes with lenses, retinas and corneas, similar to human eyes. Scientists believe that they can form images, and possibly see colour. However, a mystery still surrounds how exactly they do this, for they have no brain in the metazoan sense (they lack mesoderm, the tissue from which the brain develops, and they lack cephalization, or the nervous system controlling the body from the head).

Diagnosis

Medusae with cuboid bodies, with tentacles issuing from branched or simple interradial pedalia; sensory organs 4, in perradial niches in bell wall, each in the form of a complex rhopalium with typically 2 median lensed eyes, 4 lateral eye spots, and a single large statolith; a well developed velarium venated by radial extensions of the gastrovascular space; coelenteron partitioned vertically into an upper, horizontal gastric region and a lower, vertical gonadal region, and radially into 4 large pockets separated at the interradial corners by septa; gastric phacellae, when present, endodermal at the interradii of the stomach; gonads endodermal, typically as paired lateral leaves along the interradial septa, but may also grow into the gastric saccules; mesoglea cellular; cnidome typically including microbasic mastigophores, euryteles, and isorhizas, borne on tentacular rings and often in warts or freckles on the exumbrella; planula larva teardrop-shaped, with a whorl of dark dots near the larger, anterior end; metamorphosis complete, with the cubopolyp developing into the juvenile cubomedusa, rarely leaving a viable polyp and never with an ephyra; polyp with a single large nematocyst or cluster of nematocysts in the tips of the tentacles.

ID Keys

Artificial Key to Australian Cubozoa (from Gershwin, 2005a)

1a. Stomach area with gelatinous protrusions into bell cavity, smoothly rounded or cock’scomb-
shaped; tentacles numerous, clustered on 4 branched pedalia ............................ 15
1b. Stomach area lacking gastric saccules or knob-like protrusions; with 4 or 8 tentacles, borne
singly on 1 or 2 separate unbranched pedalia per corner…….…………………....…… 2
2a. With single tentacle on each of 4 interradial corners ……………..……………..…….…… 3
2b. With 2 tentacles per interradial corner; Darwin region …………….……... Tripedalia binata
3a. Gastric cirri lacking; rhopaliar niche ostium frown-shaped (with 1 upper and 1 lower
covering scales) .………………………………………………………..…………...…. 4
3b. Gastric cirri present in brush-like bundles or in horizontal or crescentic rows in the corners
of the stomach; rhopaliar niche ostium heart-shaped or T-shaped .…………………... 11
4a. Body small (ca 1-1.5 cm) and warty; tentacles decorated with widely-spaced handkerchieflike
nematocyst bands; pedalial canals simple ………………..……………………….. 5
4b. Body medium-sized (2-6 cm); tentacles otherwise; nematocyst bands with many fine
regularly-spaced halo-like bands which contain nematocysts inserted end-wise, or with
unadorned bands; pedalial canals with or without upward-pointing spike……………...6
5a. Body small (1 cm), with conspicuous gelatinous mammillations; tentacles with or without
minor nematocyst bands, but lack unarmed bands; velarial canals 2 per octant, simple;
rhopaliar horns long and narrow; N. QLD ….......................................... Carukia barnesi
5b. Body about 1.5 cm, smooth but with low rounded nematocyst warts; tentacles with about 14
fine unarmed bands between successive handkerchief bands; velarial canals 2 per
octant, branched, each with 1 large nematocyst wart; rhopaliar horns long and narrow,
capitate; Broome region ………...….…..............................................… Carukia shinju
6b. Tentacles with halo-like nematocyst bands ………………..…………………………….…. 7
6a. Tentacles with “normal” cubozoan nematocyst bands, lacking halos …..…………..……… 8
7a. Body 3-4 cm, lacking gelatinous protuberances; with complexly branched velarial canals;
with narrow triangularly-shaped perradial lappets with 2 rows of 3-4 nematocyst warts;
with relatively short, broad, inwardly-curved rhopalial horns; northern QLD
………....………………………………….………………………..….. “Halo-Irukandji”
7b. Body about 2 cm tall, with halo-like tentacle bands; with 2 velarial canal in each octant,
single main canal broadly bifurcated, and a narrow ad-interradial; with large, rounded
beehive-shaped perradial lappets, with a single large nematocyst wart on one side of the
lappets; with broad, nearly vertical rhopaliar horns; Dampier region
…………………...……………….……………………………..…. “Dampier Irukandji”
8a. Pedalial canal with prominent upward pointing spike at the bend ……………….……...…. 9
8b. Pedalial canal without prominent spike at the bend ……………………...…………..…… 10
9a. Bell extremely large (10-15 cm or more); tentacles wide and flat, flaring at top; velarial
canals extremely numerous and pinnate; coastal QLD & NSW ................... “Morbakka”
9b. Bell smaller (3-5 cm); pedalial canals square in cross section along most of length; velarial
canals dendritic and diverticulated, with 2 rows of conspicuous round nematocyst
patches on perradial lappets; Darwin area ..….................................. Gerongia rifkinae
10a. Body up to about 5 cm, with a noticeably flat top; with variable pedalial canal bend form,
but never spiked; 1 velarial canal root branching into about 4 simple, crooked canals per
octant; rhopalial horns short and broad, often curved inward like Viking horns; offshore
Broome area ………………......................................................…… Malo maxima
10b. Pedalial spike reduced to a nub; bell typically 3-4 cm, taller than wide, with a rounded top;
1 palmate velarial canal per octant, with numerous simple branches; northern QLD
……………………….……………………………………………… “Pseudo-Irukandji”
11a. Stomach flat, completely lacking mesenteries; phacellae in large crescentic bundles in
corners of stomach, with long cirri; velarial canals 3 per octant, of variable form
typically simple; rhopaliar niche ostium T-shaped (with 1 upper and 2 well developed
lower covering scales) ..………………………….…….…......................................…. 12
11b. Phacellae in brush-like bundles or in oblique rows across stomach corners; stomach flat,
with poorly developed mesenteries; velarial canals 2 per octant, biforked or complexly
branched; rhopaliar niche ostium heart-shaped (with 1 upper and 2 vestigial lower
covering scales), or open (lacking covering scales) ……….......................................... 13
12a. Bell to 10 cm, exceedingly taller than wide; cirri in crescentic rows of long parallel
filaments; nematocyst freckles very tiny, evenly scattered; velarial canals simple, 3 per
octant; rhopalial niches T-shaped; GBR .……………………...... Alatina mordens
12b. Bell to about 2 cm, with very minute sparsely scattered nematocyst freckles; with butterflyform
gonads, attached only in the center region of the interradial septa; with very long
pedalial stalks; GBR ………….………………………………… Alatina rainensis
13a. Rhopaliar niche ostium heart-shaped ………………...…...…………...……………….… 14
13b. Rhopaliar niche ostium like a vertical key-hole, lacking covering scales; bell minute,
typically less than 1 cm, with adhesion pads near apex which may or may not be visible;
tentacles banded brown and orange; N. QLD …………………......… Carybdea sivickisi
14a. Phacellae in single-rooted brush-like dendritic bundles; bell about 1-2 cm, with scattered
nematocyst freckles; velarial canals 2 per octant, of 2 forms: those nearest the rhopaliar
radii simply dichotomous, those nearest the pedalial radii complexly dichotomous;
rhopalial niches heart-shaped; Southern WA and Far North QLD
…………………………………………...……………………...…Carybdea xaymacana
14b. Phacellae in elongated rows, set obliquely across stomach corners; bell 3-4 cm; cirri in
horizontal rows of small bundles; nematocyst freckles scattered over bell and along
pedalial outer keel; velarial canals 2 per octant, biforked; rhopalial niches heart-shaped;
SA and Southern WA …………………………………………...…… Carybdea rastonii
15a. Body well pigmented with brownish spots; subumbrella with horizontal muscle bands;
gastric saccules absent; gonads filamentous; GBR……….....……. Chirodectes maculatus
15b. Body typically transparent and colourless ………………………...……………………... 16
16a. Pedalial canal with upward-pointing thorn at bend; with cockscomb-like saccules that are
functioning gonads; up to 4 x 15 tentacles, flat in cross section and thick; body size to
38 cm, lethal above 8-10 cm; tropical Australia …................................ Chironex fleckeri
16b. Pedalial canal lacking thorn, typically knee-shaped; tentacles fewer than 10 per corner,
round and fine; gastric saccules sessile, knob-shaped or coalesced ..........................… 17
17a. Pedalial canal bend rounded or with sharp 90° angle, lacking thorn; gastric saccules solid,
smoothly rounded, separate knob-like swellings; up to 4 x 9 fine, round tentacles; body
size 8-10 cm; northern QLD ……………….....……… Chiropsella bronzie
17b. Pedalial canal bend rounded, lacking thorn; gastric saccule pairs coalesced into a single,
solid, kidney bean-shaped swelling; up to 4 x 6 fine, round tentacles; body size to about
5 cm; Arnhem Land, N.T. ……..…....................................Chiropsella bart

General References

Franc 1995. Classe des Cubozoaires. pp. 885-922 in D. Doumenc & J. Bouillon (eds). Traité de Zoologie. Paris : Masson. [885-922] (In French)

Gershwin, L. 2005. Taxonomy and phylogeny of Australian Cubozoa. Unpublished PhD thesis. School of Marine Biology and Aquaculture, James Cook University, Townsville, QLD. 221 pp. 49 pls

Haeckel, E. 1880. System der Acraspeden. Zweite Halfte des System der Medusen. Jena : G. Fischer. [423-449, 640-641, pls 25, 26] (In German)

Werner, B. 1984. Klasse Cubozoa. Lehrbuch der Speziellen Zoologie. H. E. Gruner. Stuttgart, Gustav Fischer Verlag. 2: 106-133. pp. 106–133 in Gruner, H.E. (ed). Lehrbuch der Speziellen Zoologie. Stuttgart : Gustav Fischer Verlag. [106-133] (In German)

Williamson, J., Fenner, P., Burnett, J. & Rifkin, J. (eds) 1996. Venomous and Poisonous Marine Animals: a medical and biological handbook. Sydney, Australia : NSW University Press 800 pp.

History of changes