Tuesday, 17 September 2019

Watching starfish move

All of us who enjoy looking in coastal rock pools are pleased when we find a starfish sheltering under a stone, or under fronds of algae. When we pick up our specimen, we see that the undersides of its arms bear many tube feet that are used both in locomotion and also as a means of obtaining food. Their use is explained in the following video clip [1]:

In the Nineteenth Century, our knowledge of starfish locomotion was dependent on written accounts, aided by illustrations, and no-one was better at describing the animals of the shore than Philip Henry Gosse. In Land and Sea, Gosse writes of a visit to Meadfoot Beach in Torquay to explore the rock pools there (see below), a collecting site within easy walking distance of his home [2].

Gosse found a large starfish in the Meadfoot rock pools and moved it to another pool that provided a better chance of detailed study, as the animal was too large to take back to his aquarium. His description in Land and Sea [2] of its locomotion provides an interesting comparison with the video recording above. In reading it, we can admire Henry Gosse’s ability as a writer and it is easy to see how he was such an important figure in the development of the “Marine Biology Craze” of the Victorian era:

I mark it gliding smoothly, and with a moderate rapidity, over the unevenness of the rocky bottom, and notice the mechanism by which its progression is effected, I see at once that I have before me one of the great types of animal locomotion; a series of contrivances, by which a given end, that of voluntary change of place, is accomplished, which are quite sui generis; admirable in their adaptation to the prescribed end, but totally unlike the arrangements by which the same object is attained in higher forms of life..

..Each of the five thick and bluntly-pointed arms, or rays, of this star-like animal is seen to be indented on its underside by a rather wide and deep furrow, which extends from the hollow in the centre, where the mouth is seated, throughout its length, to the point. Along the floor of this groove we should see in the dead and dried animal four rows of minute perforations, running lengthwise. We cannot discern them directly during the living activity of the starfish, because the crowding sucker-feet conceal them. Each of these suckers is a tube of delicate membrane, a continuation of the common skin; and its interior accurately corresponds with one of these perforations in the skeleton..

..If we were to dissect this animal, we should find, on the interior surface of the semi-crustaceous integument of the arm, a little globular bag of similar transparent membrane, on each aperture, which opens into the cavity of the globe, just as on the outer side it opens into the tube. Thus there is a free intercommunication between the globose sac on the inside and the sucker-tube on the outside, through the tiny perforation in the crust. The interior is filled with a clear fluid, scarcely differing in its nature from sea-water. The globular sac within and the tube without are both composed of highly contractile tissue, under the control of the animal will.

Gosse goes on to describe the stepping motion of the tube feet, but does not describe the complete water vascular system, its connection to the surrounding sea water via the madreporite (the porous plate shown in the video), or the nervous system by which the movement of the tube feet is controlled. Being a devout Christian, he does, however, state:

Here we have one of the multitudinous results of the infinite Wisdom and almighty Power combined in creation. The problem is to endow with the faculty of voluntary locomotion a sentient creature which has no internal skeleton, and no limbs. It is solved in many ways in the invertebrate classes, and this is one example.

While writing this, Gosse was aware that there was a growing acceptance of the theory of evolution (Darwin having published On the Origin of Species in 1859), something which he vehemently opposed, as he believed in a literal interpretation of the story of Creation in the Book of Genesis. He looked upon the wonderful complexities of the natural world as the work of an all-powerful God.

I, too, am filled with amazement when looking at specimens of the same animals and plants that Gosse observed and this always presents a challenge. Coming back to the example of locomotion in starfish, I find myself trying to answer questions on how the water vascular system evolved – what were the various stages required and did they occur near-simultaneously, or gradually? Isn't the sense of wonder posed by such questions very similar to that Gosse felt about God's Creation?

[2] Philip Henry Gosse (1865) Land and Sea. London, James Nisbet & Co..

Wednesday, 4 September 2019

Pufflets, pimplets and muzzlets – Gosse and the common names of sea anemones

Philip Henry Gosse (above), together with his young son Edmund, moved to a new house in St Marychurch, Torquay in 1857. It was a tough year for him, as his wife, Emily, died of breast cancer and Omphalos, his book that attempted to resolve the conflict between Creation and the contemporary view of the geological record, was published to a hostile reception from all quarters. Against this background, Henry busied himself with collecting on the shore and working on describing the British sea anemones and corals. He published what was to become Actinologia Brittanica in 12 parts from 1858 to 1860 and the parts were gathered into a book that was published in 1860 [1,2]. I am fortunate to own a first edition of the book and I have also seen many of the original paintings by Gosse on which its illustrations are based [3].

To many, sea anemones and corals may seem an odd subject for study, yet these primitive animals fascinated many Victorian collectors and they gain their name because of their bright colours and the way they superficially resemble flowers. While those of scientific bent used a Latin binomial classification, others used the common names that are found in the book and which provide a splendid example of the richness of the English language. Gosse himself was aware of the colour provided by these names and, in the Preface of The Romance of Natural History [4], he wrote:  

In my many years’ wanderings through the wide field of natural history, I have always felt towards it something of a poet’s heart, though destitute of a poet’s genius.

That’s not to suggest that Gosse was not a good scientist (he was a Fellow of the Royal Society), but he recognised the value of popularising the subject. Here is a list of the common names of most British sea anemones and corals, as given by Gosse (the definite article has been omitted in each case) [1]:

Plumose anemone *
Daisy anemone *
Scarlet-fringed anemone *
Rosy anemone *
Ornate anemone
Fish-mouth anemone (*)
Orange-disked anemone *
Snowy anemone *
Sandalled anemone
Pallid anemone
Translucent anemone
Eyed anemone
Cave-dwelling anemone *
Snake-locked anemone *
Parasitic anemone *
Gold-spangled anemone
Cloak anemone *
Walled corklet *
Warted corklet
Painted corklet
Opelet *
Beadlet *
Gem pimplet *
Glaucous pimplet
Red-specked pimplet *
Diadem pimplet *
Marigold wartlet
Dahlia wartlet
Scottish pearlet
Scarlet pearlet
Arrow muzzlet *
Waved muzzlet
Trefoil muzzlet
Sand pintlet
Rock pintlet *
Painted pufflet
Crimson pufflet *
Crimson Imperial
Yellow Imperial
Globehorn *
Sandy creeplet
Furrowed creeplet *
Wrinkled creeplet
Devonshire cup-coral *
Moray cup-coral
Shetland cup-coral
Winged cup-coral
Smooth-ribbed wedge-coral
Knotted wedge-coral
Scarlet crisp-coral
Weymouth carpet-coral
Scarlet and gold star-coral

* = collected by Gosse from the shores around Torquay
(*) = sent to Gosse, having been collected by others from the shores around Torquay

Of the 61 types of sea anemone and coral in this list, 22 (36%) were collected by Gosse from the coast around Torquay. Although an excellent area for discovering these fascinating creatures, the high number reflects Gosse’s industry rather than this coast being a mecca for the animals. As an example of his industry, he remarks that the area shown in the image below was an especially good one for sea anemones, if one ventured by small boat to explore the cracks and fissures during low spring tides.

Anyone reading the list, and who wishes to escape the superficiality of the modern world, will be struck by the beauty of the names. My favourites are the red-specked pimplet, the dahlia wartlet, and the crimson pufflet: Gosse’s illustrations of these sea anemones, scanned from my copy of Actinologia Britannica, are shown below (in order).

I’m sure you will have your own favourites and, like Gosse, be stimulated to find examples during visits to the British coast.

[1] Philip Henry Gosse (1860) Actinologia Britannica: a history of the British sea-anemones and corals. London, John Van Voorst.

[2] R.B.Freeman and Douglas Wertheimer (1980) Philip Henry Gosse: A bibliography. Folkestone, Wm. Dawson & Sons Ltd..

[4] Philip Henry Gosse (1860) The Romance of Natural History. London, J.Nisbet & Co.