Poisoned Lances

Dominion, Volume 28, Issue 92, 12 January 1935, Page 20

Poisoned Lances

(By

J. DRUMMOND,

F.L.S., F.Z.S., for “The Dominion.”)

FAIRLY plentiful on sandy beaches in New Zealand arc empty shells about the same size as an orange, but flattened on one side, and covered with bosses in symmetrical patterns. The bosses are ornaments on pieces of shelly plate armour, designed and wrought by the creatures that lived inside. The plates of each shell fit closely edge to edge. They are arranged pentamerously, that is in fives. Pentamerous symmetry is common in flowers, but is unknown in the animal kingdom except in this group, and not in all of them. When the occupier was alive, long sharp spines fixed on ball-and;.socket joints sprang from the bosses. Before waves, rocks and boulders broke the spines off they were distributed over the surface of the shell. They helped slightly in locomotion. They gave the shell the appearance of a hedge-hog. In former times a hedge-heg was called a<n urchin. It has lost that name, but this creature of (he sea, which is in no way reflated to it, retains the title ofn sea-urchin, solely on account of its spines. In addition, a sea-utchin has tube-feet, equipped with suckers. It can walk on the tips of its spines, hut it usually fixes the suckers of its lube-feet to a rock or other objectami pulls lt<elf along. Thlong spines are the most conspicuous appendage. and the tube-feet are the most useful. Another set of appendages is the most remarkable. They look like secondary spines. They workon the same principle as pincers or three-bladed scissors. They keep the shell clean, remove anything, dead or alive, that should not be on the shell, sometimes hold a piece of seaweed over the shell in order to conceal it, and, more important, defend the dwelling and the occupier, by biting enemies and pouring into the wounds poison stored in bags.

'Fhe virulence of the poison was proved when a bite caused a frog’s heart to stop beating. A starfish was seen approaching a seaurchin aggressively. The sea-urchin’s long spines separated widely, and the blades were fixed into the starfish, which retreated, wrenching the blades out of their position. The starfish returned to the attack several times, always with the same result. The starfish wrenched off all the blades, wrapped itself over the sea-urchin, and smothered it. A sea-worm bitten by the snapping blades took cramp immediately, and died in a few minutes. The blades used in this encounter were torn off at their base. The dead sea-worm was thrust from the sea-urchin’s shell. It is not unusual for fhe blades to hold on to an enemy with a bull-dog grip until they are torn off. This may not be sdrious to the sea-urchin, as it can provide itself with fresh blades. On some sea-urchins, all the blades may not be used at the same time. An enemy may be held hy two and smashed with the third. Zoologists affirm that a sea-urchin is devoid of a brain as the word is generally understood. Each blade and each spine acts on its own responsibility, automatically, by reflex action. A seaurchin has so many automatic movements that it has been called a republic of reflexes. I’ut neatly by an epigrammatic zoologist: “In a dog, the animal moves its legs; in a sea-urchin, the legs move fhe animal.”

Some species of sea-urchins have a poison-bag near the (ip of each long spine. If the sharp tip of the spine pierces a person’s skin

and is broken, off, the poison enters the wound. The result, according to Sir J. Arthur Thomson, is a painful wound, often slow to heal * Something of this nature, apparently, happened to a resident of Queen Street, Onehunga, who signs his letter with his initials. ".I.I)." “When I lived at Apia, Samoa,” he writes, “I often went with a friend at low tide to the outer reef. During one visit, we saw something in the water that looked like a shell with hollow projections, shaped like miniature battleship guns, about five inches long, as thick as a lead pencil. My friend put his hand into the water, but quickly withdrew it. Sticking into the top of one of his fingers there were several fragile shafts about the size of fine sewing needles, absolutely straight, jet black. With a steady pull I withdrew all, but did not break the barbs. The shafts wore brittle, and evidently poisonous, as inflammation set in at once and continued for several days. We did not inquire further into the creature’s habits, and are ignorant of its identity." In reply to a request, the Secretary to the Administration of Western Samoa had many inquiries made on the subject. He has courteously replied that the creature is a species of sea-urchin, which Samoans call “vana.”

Maoris used sea-urchins for food. Samoans probably use their sea-urchins in the same way. Sea-gulls, hungry lovers of shellfish, somelimes take sea-urchins in shallow water, fly into the air with them, drop them on to rocks or hard sand, smashing the shells and devour the seaurchins. Many enemies beset sea-urchins. They need their cuirasses and their poisoned lances and blades; but Sir J. A. Thomson noted that an average sea-urchin’s most dangerous time is in its early youth. It spends its youth as a tiny being in the open sea, away from the turbulent life near the shore. It has no resemblance to an adult sea-urchin. It is transparent, and is like an inverted easel with many legs. An adult female of the common species in the Old Country produced 20,000,000 eggs in a single season. Delicate, palatable and defenceless, swimming freely in countless numbers, the water thick with them, youthful arc among the edible things of the sea, and the mortality among 'them is very great. <■> Sea-urchins in an aquarium were hyper-sensitive to light and shade. Strong light irritated their skins, and they sought the darkest corner. If they continued in the strong light, their supines rotated. A Mediterranean sea-urchin, equipped with long spines, reacts to a shadow cast by a cloud or by a passing fish. It erects its spines as if to ward off an intruder. Snapping blades were seen in action when a shower of powdered chalk was poured on a captive sea-urchin. The blades seized the particles, broke up any lumps there were, and reduced the whole to an impalpable powder, which was quickly removed by fine hairs that covered the skin. The blades were brought into action by any prolonged irritation of the skin, such as bright light and showers of particles of grit or mud. Acid, applied to a sea-urchin's skin, causes the spines to bend to all points of the compass, to rotate. Under stimulation that, is too strong, the first spines affected, strike those next to them vehemently.