Glimpses of Ocean Life 30

Glimpses of Ocean Life 30

This wonderful race of animals, for their beauty of colour, elegance

of shape, and peculiarity of structure, possess a great degree of

interest, not only to the naturalist, but also to the casual observer

by the sea-side.

 

There are fourteen British species of Asteriadæ, which are arranged

under four families, namely--the Urasteriæ, the Solasteriæ, the

Gonasteriæ, and the Asteriæ. This group contains no less than eight

generic types, clearly distinguished from each other by certain

characters, 'derived from the outline of the body, the number of rows

of suckers in the avenues, and the structure and arrangement of the

spines covering the surface and bordering the avenues.'

 

There are four species of Star-fishes belonging to the genus Uraster,

the most common of which is the _Uraster rubens_, or Common Cross-fish.

 

No person in the habit of visiting the sea-shore can be unfamiliar with

the likeness of this creature, which is generally seen lying wedged

in some rocky crevice, or among the Fuci, there patiently waiting the

return of the tide.

 

At such a time, the Devil's-hand (as the Irish people term it), does

not appear by any means attractive. If placed in water, however, its

appearance becomes wonderfully improved.

 

Here is a small specimen, just brought from the sea-shore at

Cockburnspath (a most romantic and delightful locality, situated on

the coast of Berwickshire). It is neatly wrapped up in a mantle of

sea-weed. Freed of its verdant envelope, I deposit the youthful Rubens

upon his back--'willy-nilly'--in a tumbler partly filled with clear

sea-water, and then proceed to watch its movements through a magnifier.

 

At a glance we perceive that each of its five rays is grooved on its

lower surface, and filled with minute perforations, through which is

gradually protruded a multitude of fleshy suckers, knobbed at the end.

It is by aid of these organs that the animal grasps its food, and

changes its position, as we shall presently see. One of the rays is now

slowly lifted up and moved about in various directions, while from its

extreme point the suckers are extended to the utmost limit. No sooner

do they touch the side of the vessel than they are firmly fixed and

contracted. A _point d'appui_ being thus gained, the animal is enabled

by degrees to draw its body round, so as to get another regiment of

suckers into play, and, by such plan of operations being repeated,

the animal is eventually enabled to 'right itself,' and crawl up the

polished surface of the glass.

 

Generally, when the Star-fish is disturbed, or placed on a dry piece

of stone, the suckers are withdrawn into the body, leaving no signs

of their previous existence except a series of minute tubercles. In

fact, the Asterias, although enabled to adhere with great tenacity to

any foreign object when immersed in water, possesses but little power

to retain its hold if the fluid be removed. Hence the young zoologist,

keeping this peculiarity in mind, should not too hurriedly return a

verdict of 'Found dead,' when he meets with a helpless specimen upon

the beach, for in all likelihood, were the creature to be laid for a

few minutes in a rock-pool, it would soon exhibit signs of returning

animation.

 

A simpler, though not so sure a test for ascertaining whether a

Star-fish be living or not, is to handle the specimen. If it feels soft

and flabby, it is dead; but if tolerably firm to the touch, it may be

'recalled to life,' by the means pointed out.

 

It may not be out of place to chronicle here a singular circumstance

which the writer has often verified in connection with the true

Star-fishes. It is this. When any captured specimens have been placed

in confinement, no matter how large or small such might be, they never

moved through the liquid element with a tithe of the rapidity that I

well knew they were capable of. At the sea-side, I have seen a specimen

of the Cross-fish glide through the water so nimbly, yet withal so

gracefully, that I have felt inclined to rank natation among the few

other acomplishments of which the species can boast.

 

The _Uraster rubens_ is also popularly known as 'Five Fingers.' For

ages past it has been subject to the bitter denunciation of fishermen

and others, for the injury which it is said to inflict upon oysters.

At one time, according to Bishop Spratt, the Admiralty Court laid

penalties upon those engaged in the oyster-fishing who did not

tread under their feet, or throw upon the shore, a fish they call a

Five-Finger, resembling a spur-rowel, because that fish gets into the

oysters when they gape, and sucks them out. Poets have also endeavoured

to perpetuate the vulgar opinion:--

 

'The prickly Star-fish creeps with fell deceit,

To force the Oyster from his close retreat,

Whose gaping lids their widened void display;

The watchful Star thrusts in a pointed ray--

Of all its treasures robs the rifled case,

And empty shells the sandy hillock grace.'

 

Even yet the oyster fishermen at certain localities wreak all

possible vengeance upon the 'submarine Dando's,' for their supposed

gourmandizing propensities. I say _supposed_, for although so

many naturalists have studied the question, it is not, up to the

present time, satisfactorily settled. Some deny the alleged tendency

altogether, while less sceptical observers are unable to understand

the mode in which the Star-fish could injure an animal apparently so

capable of self-defence as the oyster. According to certain authors,

the Star-fish encircles the oyster with its five fingers, and by some

clever process of suction destroys the unfortunate mollusc. Others,

again, maintain that the first step of the attack is the injection

of some marine chloroform between the shells of the oyster, and that

during the insensibility that follows, the Star-fish effects an

entrance.

 

As this is an interesting subject, perhaps the reader would like to

have the exact words which are used by two celebrated naturalists, one

of whom attempts to vindicate the character of the Asteridæ, the other

to blacken it.

 

Sir John Dalyell--a high authority upon all matters of marine

zoology--shrewdly remarks: 'I have not heard it suggested that the

Star-fish possesses any kind of solvent compelling the bivalves

to sunder. Neither can its hostility be very deadly to the larger

univalves, from the distance to which they are enabled to retreat

within their portable dwellings. Their general habits are, to force the

shells of smaller bivalves asunder, and to devour the contents; they

likewise consume the substance of ordinary fishes entire; nevertheless,

as far as I am yet aware, their destruction of oysters is destitute of

evidence. The Star-fish sometimes shows an eversion of stomach, or of

some membrane of it. Whether this may be the means of affecting their

prey, merits investigation.'

 

Professor Jones, who affirms that in the latter suggestion Sir J.

Dalyell has nearly hit upon the true solution of the problem, thus

gives what _he_ considers to be the correct mode of procedure on the

part of the Star-fish: 'Grasping its shell-clad prey between its rays,

and firmly fixing it by means of its prehensile suckers, it proceeds

deliberately to turn its stomach inside out, embracing in its ample

folds the helpless bivalve, and perhaps at the same time instilling

some torpifying fluid, for the shells of the poor victim seized soon

open, and it then becomes an easy prey.'

 

Now, many fishermen with whom I have conversed hold the same opinion as

Bishop Spratt, and believe that when the oyster is gaping the Star-fish

insinuates a finger, and hastily scrapes out the delicious mouthful;

nay, further maintain that the Star-fish is far from being successful

at all times, very often, especially when there has only been one ray

inserted, the frightened oyster grasps it with all his might, and

obliges his discomfited opponent to retire minus a limb.

 

If the writer might venture to suggest an opinion, he would express

his belief that the following is the correct account of the state of

matters. He believes with the fishermen that frequently the star-fish

begins his attack by inserting an arm, but he does not believe that the

oyster under such circumstances escapes with life. Let us suppose the

star-fish to have succeeded in insidiously introducing a ray within the

shell of the apathetic oyster, and that the oyster immediately resented

such intrusion by closing his shell with all the force he can exert.

The opposite argument at this stage is, that the intruder is obliged

from _pain_ to abandon his hold, and even pay for his audacity by the

forfeit of a limb. But against this we advance the notorious fact, that

the star-fish, like so many marine creatures of a similar organization,

is remarkably indifferent to pain. I therefore believe the true

explanation to be, that the oyster being unable to sustain such

continued muscular exertion for nearly so long a time as the star-fish

can tolerate the pressure upon its ray, the latter is consequently, in

the long run, successful.

 

The number of rays in the several genera of the true Star-fishes is

extremely various. In the genus _Uraster_, as we have seen, five is

the predominant number. If we turn to the two species which comprise

the genus _Cribella_, we still find the quintuple arrangement adhered

to. In _Solaster endeca_, on the contrary, the rays vary from nine

to eleven, and even reach as high as twelve or fifteen in _Solaster

papposa_.

 

In the genus _Palmipes_ we have the pentagonal form, it is true, but

the space between each ray is filled up, so as to resemble the webbed

foot of a bird, hence the popular title of this solitary species,

'The Bird's-foot Sea-star.' 'It is the flattest of all its class, and

when alive it is flexible like a piece of leather.' Passing by the

'Cushion-stars' (which have five _angles_--it seems a misnomer to call

them rays), which connect the true Star-fishes with the Sea-Urchins,

we come lastly to the 'Lingthorn,' _Luidia fragillisima_, with its

seven rays. This is the animal of which Professor Forbes discourses so

pleasantly about its winking derisively at his despairing endeavours

to preserve even a small portion of what at that time was his maiden

specimen. The Luidia is even more brittle--more regardless of its

wholeness, than the _Ophiuræ_, which renders the capture of a perfect

specimen a most difficult task.

 

 

 

 

CHAPTER XIX.

 

Sea-Urchins (Sea-Hedgehogs).

 

 

'Truly the skill of the Great Architect of Nature is not less displayed

in the construction of the Sea-Urchin than in the building up of a

world.'--P. FORBES.

 

 

 

 

[Illustration:

 

1 THE APLYSIA or SEA-HARE

2 PURPLE-TIPPED SEA-URCHIN

3 Spine of PURPLE-TIPPED SEA-URCHIN

4, 5 Suckers of PURPLE-TIPPED SEA-URCHIN

6 COMMON SUN-STAR]