Glimpses of Ocean Life; Or, Rock-Pools and the Lessons they Teach

by John Harper

Although apparently sedentary creatures, the Actiniæ often prove themselves to be capable of moving about at will over any portion of their subaqueous domain. Having selected a particular spot, they will ofttimes remain stationary there many consecutive months. A smooth anemone that had been domesticated for a whole year in my aquarium thought fit to change its station and adopt a roving life, but at last 'settled down,' much to my surprise, upon a large mussel suspended from the surface of the glass. Across both valves of the mytilus the 'mess.' attached by its fleshy disc, remained seated for a considerable length of time. It was my opinion that the mussel would eventually be sacrificed. Such, however, was not the case, for on the zoophyte again starting off on a new journey, the mollusc showed no palpable signs of having suffered from the confinement to which it had so unceremoniously been subjected.

The appearance of this anemone situated several inches from the base of the vessel, branching out from such an unusual resting-place, and being swayed to and fro, as it frequently was, by the contact of a passing fish, afforded a most pleasing sight to my eye. Indeed, it was considered for a while one of the 'lions' of the tank, and often became an object of admiration not only to my juvenile visitors, but also to many 'children of larger growth.'

There is a curious fact in connection with the Actiniæ which deserves to be chronicled here. I allude to the apparent instinct which they possess. This power I have seen exercised at various times. The following is a somewhat remarkable instance of the peculiarity in question.

In a small glass vase was deposited a choice A. dianthus, about an inch in diameter. The water in the vessel was at least five inches in depth. Having several specimens of the Aplysiæ, I placed one in companionship with the anemone, and was often amused to observe the former floating head downward upon the surface of the water. After a while it took up a position at the base of the vase, and remained there for nearly a week. Knowing the natural sluggishness of the animal, its passiveness did not cause me any anxiety. I was rather annoyed, however, at observing that the fluid was becoming somewhat opaque, and that the Dianthus remained entirely closed, and intended to find out the cause of the phenomena, but from some reason or other failed to carry out this laudable purpose at the time. After the lapse of a few days, on looking into the tank, I was delighted to perceive the lace-like tentacula of the actinia spread out on the surface of the water, which had become more muddy-looking than before.

I soon discovered that the impurity in question arose from the Aplysia (whose presence in the tank I had forgotten) having died, and its body being allowed to remain in the vessel in a decaying state. The deceased animal on being removed emitted an effluvium so intolerably bad that it seemed like the concentrated essence of vile odours. The water, of course, must have been of the most deadly character, yet had this most delicate of sea-anemones existed in it for several consecutive days.

In order further to test how long my little captive would remain alive in its uncongenial habitation, I cruelly refused to grant any succour, but must own to having felt extremely gratified at perceiving, in the course of a few days, that instead of remaining with its body elongated to such an unusual extent, the Dianthus gradually advanced along the base, then up the side of the vessel, and finally located itself in a certain spot, from which it could gain easy access to the outer atmosphere.

After this second instance of intelligence (?) I speedily transferred my pet to a more healthy situation.

Having procured a small colony of Actiniæ, you need be under no anxiety about their diet, for they will exist for years without any further subsistence than is derived from the fluid in which they live. Yet strange as the statement will appear to many persons, the Actiniæ are generally branded with the character of being extremely greedy and voracious. 'Nothing,' says Professor Jones, 'can escape their deadly touch. Every animated thing that comes in contact with them is instantly caught, retained, and mercilessly devoured. Neither strength nor size, nor the resistance of the victim, can daunt the ravenous captor. It will readily grasp an animal, which, if endowed with similar strength, advantage, and resolution, could certainly rend its body asunder. It will endeavour to gorge itself with thrice the quantity of food that its most capacious stomach is capable of receiving. Nothing is refused, provided it be of animal substance. All the varieties of the smaller fishes, the fiercest of the crustacea, the most active of the annelidans, and the soft tenants of shells among the mollusca, all fall a prey to the Actiniæ.'

This is a sweeping statement, and, although corroborated by Sir J. Dalyell and others, is one that requires to be received with a certain degree of caution. It most certainly does not apply to A. bellis, A. parisitica, A. dianthus, troglodytes, or any other members of this group; and to a very limited extent only is it applicable to A. coriacea or A. mesembryanthemum.

As may readily be conceived, the writer could not keep monster specimens, such as are often found at the sea-shore; but surely if the statement were correct that, as a general rule, the actiniæ eat living crabs, the phenomenon would occasionally occur with moderate-sized specimens, when kept in companionship with a mixed assembly of crustaceans. Yet in no single instance have I witnessed a small crab sacrificed to the gluttony of a small anemone.