Glimpses of Ocean Life 33

Glimpses of Ocean Life 33

On closely examining the spot pointed out, and turning over some fronds

of Dulse, we came upon a small fleshy ball of a dark brown colour,

from which there still issued a fluid of vivid crimson hue. Having

placed this strange object in a bottle, I soon pronounced it to be an

Aplysia, with whose full-length portrait, as represented in books, I

had previously been made acquainted.

 

The power which this animal possesses, under irritation, of spurting

out a peculiar secretion, I also remembered to have seen mentioned by

several writers on natural history.

 

Although generally believed to be gentle and perfectly harmless, yet,

as Professor Forbes observes, few molluscs have had a worse character

than the Aplysiæ. From very ancient times they have been regarded with

horror and suspicion; and many writers on natural history, conversant

with them only through the silly stories of ignorant fishermen,

have combined to hold them up as objects of detestation. To touch

them, according to European prejudices, was sufficient to generate

disease in the foolhardy experimenter; while Asiatics, reversing

the consequences, maintained, perhaps with greater truth, that they

met with instantaneous death when handled by man. Physicians wrote

treatises on the effects of their poison, and discussed the remedies

best adapted to neutralize it. Conspirators brewed nauseous beverages

from their slimy bodies, and administered the potion confident of its

deadly powers. Every nation in the world on whose shores the poor

Sea-Hares crawled, accorded to them the attributes of ferocity and

malignant virulence, although there never appears to have been the

slightest foundation for a belief in their crimes.

 

A specimen of the Aplysia that I had in my tank deposited a stringy

coil of spawn, which closely resembled that of the Eolis, with the

exception that the eggs, instead of being white, were of a reddish

tint.

 

 

 

 

CHAPTER XXII.

 

Serpulæ and Sabellæ.

 

 

 

 

[Illustration:

 

1, 2 SEA-URCHIN'S TEETH (Two illustrations.)

3 COMMON SEA CUCUMBER

4 COMMON RAZOR-SHELL

5 COMMON SERPULÆ, attached to a piece of stone.]

 

 

 

 

XXII.

 

 

With the exception of the Balani (Acorn-Barnacles), perhaps the most

common objects to be met with at the sea-shore are the Serpulæ.

Scarcely a rock, or shell, or bit of old china, or piece of wood, or

rusty nail, lying near low-water mark, but is encrusted with colonies

of these animals. I have a small twig of a tree by me, so thickly

coated with Serpulæ as to obscure all signs of its ligneous character,

except at each end. A shell also exhibits the same phenomenon, and

well-nigh defies the most skilful observer to define its original form

with any degree of certainty.

 

The shelly tubes of these animals are built in the form of serpents,

or twisted funnels, of a milk-white colour. Although so extremely

hard, these tubes are formed solely by an exudation from the body

of the animal--a simple marine worm. Unlike its erratic friend, the

earth-worm, the Serpula is sedentary in its habits, and at no time does

it ever leave its dwelling.

 

The delicate, but brilliant feathery plume--the only portion of the

animal ever visible--constitutes the principal mechanism by means of

which the Serpula constructs its calcareous tube.

 

A most wonderful instance of how mighty are the works which these

insignificant creatures form when congregated together in vast numbers,

and how useful such labours may sometimes be to mankind, is narrated by

Dr. Darwin in his 'Voyage of the Beagle.'

 

Being delayed by adverse winds, this gentleman made a stay at

Pernambuco, a large city on the coast of Brazil, and the most curious

object that he saw there was the reef that formed the harbour. 'I

doubt,' to use his own words, 'whether in the whole world any other

natural structure has so artificial an appearance. It runs for a length

of several miles in an absolutely straight line, and parallel to, and

not far distant from the shore. It varies in width from thirty to

sixty yards, and its surface is level and smooth; it is composed of

obscurely stratified hard sandstone. At high water the waves break over

it; at low water its summit is left dry, and it might then be mistaken

for a breakwater erected by Cyclopean workmen. On this coast the

currents of the sea tend to throw up in front of the land long spits

and bars of loose sand, and on one of these the town of Pernambuco

stands. In former times a long spit of this nature seems to have become

consolidated by the percolation of calcareous matter, and afterwards

to have been gradually upheaved, the outer and loose parts during the

process having been worn away by the action of the sea, and the solid

nucleus left as we now see it. Although night and day the waves of

the open Atlantic, turbid with sediment, are driven against the steep

outside edges of this wall of stone, yet the oldest pilots know of no

tradition of any change in its appearance. This durability is by far

the most curious fact in its history; _it is due to a tough layer, a

few inches thick, of calcareous matter, wholly formed by the successive

growth and death of the small shells of Serpulæ, together with some

few Barnacles_, &c. These insignificant organic beings, especially

the Serpulæ, have done good service to the people of Pernambuco, for

without their protective aid the bar of sandstone would inevitably have

been long ago worn away, and without the bar there would have been no

harbour,'

 

Nothing whatever appears to be known relative to the mode of

reproduction of these Annelids. I have paid much attention to the

subject, but as yet have not gained any positive information regarding

it. The only fact which I consider worthy of being chronicled is the

following: On one occasion, when quite a novice in Marine Zoology,

while observing a beautiful group of Serpulæ seated on a stone, I saw

issuing from out one of the tubes a kind of very fine dust, of a rich

crimson hue, which continued to arise for nearly an hour in spite of

repeated efforts to disperse it by aid of a camel-hair pencil. At first

I believed the 'dust' to be the 'remains' of a deceased serpula, but

afterwards found that such was not the case, the annelid being alive

and healthy. Never having seen the phenomenon since, it has been a

great source of regret to me that I did not endeavour to discover what

the dust was composed of; but have little doubt that the microscope

would have shown it to be, in reality, the ova of the Serpula.

 

Another class of Annelidans, termed Sabellæ, like the Serpulæ, also

build habitations for themselves, but not of the same materials.

Instead of being white, the tubes of the first mentioned animals are

brown in colour, and composed of minute granules of sand, or small

shells, and lined internally with a gelatinous substance exuded from

the body of the worm. On the interior of the oyster and other shells,

and even in univalves occupied by the Lobster Crab, various tubes of

Sabellæ may often be seen. They are, however, generally discovered

congregated together, forming a kind of honeycomb mass in the fissures

of rocks, or against the sides of rock-pools, or on the surface of

small stones, &c.

 

A mass of Sabellæ tubes forms by no means an inappropriate or

unpleasant object for the tank, as the animals are hardy, and will

live for many months if the water be kept pure. Moreover, while in

confinement, they do not live in luxurious indolence, but ever seem

to be busy in the exercise of their architectural propensities, making

alterations, repairing damages, or otherwise 'sorting' their tubiculous

habitations.

 

'The tubes of the Sabellæ,' says Dr. Williams, 'are soft, flexible,

and muddy. Slimy mucus furnished by the integumentary glands of the

body is the mortar or cement, fine sand molecules are the "stones" or

solid material of the architecture. In the Sabellæ the lime of which

the tubes are built is held in solution in the mucus provided by the

cutaneous glands. It is adjusted in the fluid form, and moulded by

appropriate tools into the required shape. It then _solidifies, too,

under water_, like the "Aberthaw lime." The tube of the Sabellæ fits

closely round the body of the worm; it is slightly elastic, and the

interior is smooth.'

 

 

 

 

CHAPTER XXIII.

 

The Solen, or Razor-Fish

 

 

'His mansion he extends,

So well concealed beneath the crumbling sands.'

 

 

 

 

XXIII.

 

 

Few people who are in the habit of visiting the sea-shore but must have

noticed the empty shells of the animal about to be described. I allude

to the Solen, or Razor-Shell, commonly so called from its resemblance

to the handle attached to a barber's scythe.

 

This bivalve, improbable as the statement will appear to the

uninitiated, is one of the most efficient burrowers to be met with on

our shores.

 

By means of its fleshy foot it digs a hole in the mud or sand.

Sometimes it retreats from the surface to a distance of several feet,

but generally remains sufficiently near to allow its short, fringed

siphons to project above the sand.

 

In walking along the beach, left bare by the receding tide, the

pedestrian may often perceive little jets of water thrown up at his

approach. These jets proceed from the Razor-Fish in question. Although

we may be several yards from his burrow, his sense of feeling is so

acute, that the faintest vibration of the earth around causes the

creature to retire alarmed within his dwelling.

 

In many places the Solen is much sought after by the poor, who esteem

it a great luxury. In foreign countries--Japan, for example--it is so

highly prized that we are told, 'by express order of the prince of that

country, it is forbid to fish them until a sufficient quantity hath

been provided for the emperor's table.'

 

The Irish people, when they go out to catch the Solen siliqua, have

an appropriate song and chorus which they sing, but whether to amuse

themselves or charm the fish 'this deponent sayeth not,' for very

obvious reasons. In general, I should think the less noise the more

likelihood of success to those endeavouring to capture this animal.