Tuatara: Volume 3, Issue 2, August 1950
New Zealand Crinoids
New Zealand Crinoids
Few readers of Treasure Island are ever likely to forget Long John Silver's parrot Captain Flint, with his incessant cry of “Pieces of eight!” At any rate, R.L.S. took care to make the most of his opportunity to develop his characters' emotional responses to that notable bird in its more lurid moments. Captain Flint, however, was only an imaginary parrot—and a rather uncultured one at that, despite his literary associations. It seems unfair therefore that so few people seem to know anything of Robert, a real-life flesh-and-blood parrot, and a learned one to boot, who lived on board Her Majesty's ship Challenger some seventy years ago. Like all the best parrots in history, Robert was a grey bird; unlike some of his tribe, his was no buccaneering career—the voyage during which his name went down into history was, in fact, one of scientific exploration. Where Captain Flint was coarse, Robert was refined; for, inhabiting the zoological laboratories on the ship, where the human element was more inclined to vent its spleen in words remarkable for their length rather than terseness, poor Robert found his scope somewhat limited. His conversation was concerned with subjects like rectified spirits-of-wine rather than Jamaica rum; he was, in short, a mid-Victorian parrot. Robert originally had a mate, but the latter unwisely took a bath in a beaker of boiling potash; and so passed, or rather dissolved, away. Robert's greatest achievement in scientific conversation was to exclain “What! Two thousand fathoms and no bottom! Ah! Dr. Carpenter, F.R.S.!” Just what comment Dr. Carpenter (F.R.S.) had to make when he heard the tale does not seem to have been put on record, but we can be quite sure that he was more than satisfied with the splendid hauls that were made when the Challenger's dredge did find the ocean-bottom off the coasts of New Zealand. For it was to Carpenter that the task fell of describing the crinoids discovered on the voyage—the feather-stars and sea-lilies, plant-like animals of great scientific interest and usually of considerable beauty.
The entire crinoid fauna of New Zealand so far known, save for three species of feather-stars, was discovered on three days in the winter of 1874. It was on July 7th of that year that H.M.S. Challenger sailed out of Port Nicholson. On the 10th, then 40 miles off East Cape, the first two species of feather-stars were dredged in 700 fathoms (Station 169). On the 14th, when off Raoul Island, the best haul was obtained—seven species of feather-stars and four kinds of sea-lilies brought up from 520 fathoms. The following day yielded more sea-lilies from 600 fathoms. (Stations 170 and 171).page 79
The few deep-sea hauls made off our coasts at that time brought to light one of the most remarkable faunas ever discovered. Imagine, three and four thousand feet vertically down, almost a mile below the surface, strange animals of bizarre shapes, swimming amongst waving fields of sea-lilies of intricate delicacy of pattern and brilliant hues. Think of submarine fields lit, not by any trace of daylight from above, but by the phosphorescence of the deep-sea corals. Professor H. N. Moseley, one of the naturalists aboard, afterwards wrote of their work on July 14th, off the Kermadecs: “This is probably the richest ground dredged by us at all” (Moseley, 1879). When such outstanding success attended so short an investigation of our waters beyond the continental shelf, it might be thought that New Zealand expeditions would have been organised by now to explore the rest of our deep-sea areas. Such, unfortunately, has not been the case. Thus, the old Challenger Reports still remain the chief, or more often the only, source of information.
Over forty years elapsed before any further crinoids were discovered. In 1916 Dr. A. H. Clark of Washington, the world authority on crinoids, made known the first shallow-water feather-star, from Preservation Inlet. We still remain ignorant of many details even of this shallow-water species. In 1917 Clark recorded another species found by Mortensen near the Three Kings, while in 1918 yet another species became known from the same region. Nearly twenty years later another British Expedition passed through New Zealand waters, the Discovery, but although many Antarctic crinoids were found, only one feather-star was taken in New Zealand waters, and that a species already known. No other discoveries have been made. Few New Zealanders have ever seen any of our crinoids. Little is to be found in our museums. Even some zoologists seem to be unaware of how rich our crinoid fauna really is, and misleading statements appear in current literature. We await the day when a New Zealand deep-sea expedition works in our own region, in the zone quite near our main ports, where the off-shore waters plunge so suddenly into the mysterious depths. Meanwhile a Danish expedition is preparing to carry on the work, and is due to arrive in Wellington around New Year's Day next. May the Galathea have good fishing.
There are about 80 species of stalked crinoids so far known to science, of which five species occur abundantly in certain local deep waters. Of about 640 kinds of feather-stars, New Zealand possesses 11 species. Only 3 of the latter are known to occur in shallow waters, to wit, Comanthus benhami in the Fiords area, and Comanthus novaezelandiae and Argyrometra mortenseni both from the North Auckland area. Some of the deep-water species may well occur in shallow banks not yet investigated, just as some of the Tasman Sea sea-lilies have since been found in Bass Strait, and similar regions. No doubt many page 80 kinds remain to be discovered. Crinoids feed on small swimming animans, which they first narcotize by touching them with their delicate, but venomous, arms. According to A. H. Clark, crinoids are among the most brilliantly coloured of all animals. The large sea-lilies may be red, yellow or green. It is interesting to compare Clark's statement with an observation of Moseley, that the phosphorescence of the deep-sea corals dredged by the Challenger comprised three wave-bands, namely red, yellow and green. Thus, though inhabiting the dark abyss, such sea-lilies would be illuminated and visible in the presence of corals—for the benefit of such few denizens of those regions which happen to have eyes. Some of our New Zealand sea-lilies were found to be a dusky-purple colour, and these would be invisible. This is probably a generalized relic-pigmentation, since many shallow-water species, e.g., Comanthus benhami, are similarly tinted. Sea-lilies do not necessarily need deep water. Rather they need sheltered and clean water. Where such conditions occur in shallow areas, sea-lilies will abound. No such banks have yet been discovered off our turbulent coasts, but since we have scarcely looked for them, they may well be there.
Postscript: Since the above paragraph was written, the southern crinoid Comanthus benhami has been re-discovered. In May of this year Captain Alex Black of the “Alert” visited the Southern Fiords, with Dr. R. A. Falla and Mr. W. H. Dawbin. During the cruise Captain Black gave every facility and assistance for a dredging programme, which was carried out in each of the fiords. Five specimens of the feather-star were obtained in Doubtful Sound by Mr. Dawbin at depths of twenty to thirty fathoms. A fuller report will be published later.
Crinoids resemble starfish whose five arms have become delicate feathery structures used for capturing food, and whose disc is changed into a cup-like structure, or calyx, containing the internal organs, and supporting the arms. The mouth is on the upper surface of the calxy. Sometimes, as in Pentametrocrinus (fig. 6) there are only five arms, but more usually there is a duplication at the base of each ray, so as to produce 10 arms, as in Hypalocrinus (fig. 7), or there may be a number of branchings, as in Metacrinus (fig. 9). The arms always carry numerous pinnules, which are small tentacle-like structures arranged like the pinnae of a fern-frond on either side of the arm itself. The pinnules carry poison-glands used in the capture of food-animals. All crinoids start life as flower-like creatures, anchored by a stem arising from under the calyx (see Fig. 7). In this condition they are fixed to the sea-floor, and are called sea-lilies. Sometimes, as occurs for example in the genus Diplocrinus (Fig. II), the upper part, or crown, may become free-swimming, trailing the stem or part of the stem behind it. In such cases, other tentacle-like structures called cirri, which are arranged in circlets on the stem (at intervals called nodes), have the power of coiling around corals, etc., and so providing page 81 the animals with a means of becoming temporarily anchored once again. In the feather-stars the whole stalk is discarded very early in life, and never grows again. These crinoids are always free-swimming in the adult state, though they, too, can become temporarily anchored by means of a single ring of cirri carried on the underside of the caylx—see Fig. 5.
Key to The New Zealand Crinoids.
|1.||Animal a stalked sea-lily (fig. 7)||2|
|Animal an unstalked feather-star (fig. 5)||6|
|Each ray dividing once only, near its base, to produce two two long, slender branches (Fig 8), thus making a total of 10 arms. On the stem, 5 cirri occur at each node, and from 8 to 18 internodal joints occur between nodes. Probably pink or red in life, white in spirit. Deep water. Figs. 7 and 8.||Hypalocrinus naresianus|
|Rays dividing several times, making more than 10 arms||3|
|3.||Each ray dividing near its base into about 6 slender branches, thus making about 30 arms altogether in the crown (fig. 11). Stem having 2 and 3 cirri alternately at successive nodes, (fig. 11). Probably rose-coloured in life, yellowish-white in spirit Partly free-living, trailing the stem. Deep water.||Diplocrinus alternicirrus|
|Crown comprising more than 30 arms||4|
|4.||Each ray dividing into about 8 branches, to produce a crown of about 40 arms altogether (fig. 9)||5|
|Each ray dividing into from 12 to 16 branches, to produce a crown of 60 to 80 arms. Stem-cirri in rings of 5, separated by internodes of 8 to 9 joints. Colour in life dusky purple. Deep water.||Metacrinus nodosus|
|5.||Radial joints (i.e., those forming the basal part of the arm, before the first bifurcation) normally 4 in number. Stem with cirri in rings of 5, at intervals of 6 to 10 internodal joints. Dusky purple in life. Deep water.||Saracrinus varians|
|Radial joints normally 6 in number. Cirri in rings of 5, at intervals of 5 to 8 internodals. Dusky purple in life. Deep water. (fig. 9.)||Metacrinus wyvillii|
|6.||Rays unbranched, to make a total of only 5 arms||7|
|Rays branching, to make a total of 10 or more arms||8|
|Mouth central. Disc 5 mm. diameter. Armspread ca. 15 cms. Deep waterd. (fig. 6.)||Pentametrocrinus semperei page 82|
|8.||Lowermost pinnules on arms (i.e., those nearest disc) provided with a comb-like structure at their tips (fig. 12). Mouth displaced towards margin of disc, anus towards the centre. Littoral||9|
|No comb-like structure. Mouth at the centre of disc, anus towards the margin.||10|
|From 28 to 38 arms. Deep purplish brown colour in life. Littoral, 2 to 30 fathoms. Known only from Southern Fiords region. Armspread ca. 21 cms. (fig. 12)||Comanthus benhami|
|From 12 to 20 arms. Sublittoral; known only from region of Three Kings Islands, 65 fathoms. Disc ca. 10 mm. armspread ca. 20 cms.||Comanthus novaezelandiae|
|10.||Having 15 to 20 cirri on the aboral side of disc, the cirri long and slender, of not less than 25 segments; 10 arms.||11|
|Having relatively short cirri, of less than 25 segments; 10 to 20 arms.||12|
|About 25 cirrus segments. Disc 3 mm. diameter, armspread 6 to 7 cms. Deep water. (Fig. 1)||Thalassometra echinata|
|From 30 to 50 cirrus segments. Disc 6 mm. diameter, armspread ca. 16 cms. Deep water. (fig. 5.)||Stiremetra breviradia|
|From 60 to 70 cirrus segments. Disc 10 mm. diameter, armspread ca. 18 cms. Deep water. (fig. 13)||Aglaometra incerta|
Explanation of The Illustrations
Note: The figures are not drawn to scale; where size is of diagnostic significance, the dimensions are given in the appropriate section of the key.
Fig. 1. Thalassometra echinata—calyx, bases of some arms, and three cirri (the others are broken off).
Fig. 2. Charitometra basicurva—calyx, arms and a cirrus; note the characteristic transverse ridges on the arm-joints.
Fig. 3. Argyrometra mortenseni—calyx and arm-bases; apparently all the cirri have been broken off, leaving only the cluster of scars showing on the calyx.
Fig. 4. Glyptometra inaequalis—showing the diagnostic features.
Fig. 5. Stiremetra breviradia—calyx, part of the crown and some cirri.
Fig. 6. Pentametrocrinus semperi—the presence of only 5 arms is characteristic; 3 arms only can be seen in this side-view.
Fig. 7. Hypalocrinus naresianus—the whole animal, illustrating the general habit of a stalked crinoid, with the crown of arms surmounting the calyx, which lies at the free end of an anchored stalk. The stalk is divided into joints, and every so often a joint bears a ring of tentacle-like cirri.
Fig. 8. Hypalocrinus naresianus—characteristic mode of branching of a ray to form two slender arms, of which only the bases are here shown.
|12.||Having from 15 to 25 cirri, each of which usually comprises 18 to 20 segments, never fewer than 15 segments. From 10 to 20 arms.||14|
|Having from 25 to 80 cirri, each of which comprises 16 or fewer segments. 10 arms||13|
|From 25 to 35 cirri, each of ca. 15 segments. Disc 4 mm. diameter, armspread ca. 5 cms. (fig. 14.) Deep water.||Thaumatometra alternata|
|From 60 to 80 cirri, each of 12 to 16 segments. Sublittoral, known from North Cape and Three Kings Is. region, 60 to 95 fathoms. Disc ca. 3 mm. dia., armspread ca. 4 cms. (fig. 3.)||Argyrometra mortenseni|
|11 to 20 arms. 20 to 25 cirri, each of ca. 20 segments. Disc 10 mm. diameter, armspread 20 cms. Deep water. (fig. 4.)||Glyptometra inaequalis|
|15.||Arm joints ridged transversely (fig. 2). About 20 cirri, each of 18 to 20 segments. Disc 7 mm. diameter, armspread 20 cms. Deep water.||Charitometra basicurva|
|Arm joints smooth, not ridged. About 15 cirri, each of 15 to 18 segments. Disc 7 mm. diameter, armspread 18 cms. Deep water. Fig. 10||Charitometra incisa|
Challenger Reports, Zoology, vols. 11 and 26; Proc. Biol. Soc. Washington, vols. 29 and 31; Journ. Washington Acad. Sci, vol. 7, and also numerous papers by Austin H. Clark.page 85
Fig. 9. Metacrinus wyvillii—part of a crown, and upper portion of stem, note mode of branching of the two rays shown.
Fig. 10. Charitometra incisa—showing characters mentioned in key.
Fig. 11. Diplocrinus alternicirrus—part of a crown, and upper part of stem; note mode of branching of the ray into 6 arms.
Fig. 12. Comanthus benhami—terminal portion of an oral pinnule, showing the comb-like structure.
Fig. 13. Aglaometra incerta—showing the long, many-jointed cirrus.
Fig. 14. Thaumatometra alternata—showing characters mentioned in key.
Figs. 1, 2, 5, 6, 10, 13 and 14, after Berjeau and Highley; Fig. 3 after Th. Mortensen; Fig. 4 after Parker and Coward; Figs. 7, 8, 9 and 11 after W. S. Black; Fig. 12, H. B. Fell from a specimen in the Dominion Museum.