At the end of December 1698, Halley arrives at the Cape Verde Islands, and as he sails from Sal towards St Iago (now Santiago), he makes this interesting entry in his journal:
The Next Day at 10 in the fore-noon I past through a Streak of Water in appearance turbid, but when in it, We took up some Water, and it was full of Small transparant globules, but less than white peas intersperst with very small blackish Specks These globules were so numerous as to make the Sea of a yelow muddy Colour There Substance appear’d like that of our Squidds or Urtica Marina and there were two or three Sorts of them our people Tooke them for Spawn of Fish, but I believe them a Smaller sort of Squidds.
So what were they? My work commitments have kept me out of libraries recently and so my resources have been limited but I’ll share what I have learned.
Urtica is the Latin for nettle, deriving from the verb urere, to burn, which was rather puzzling as Halley is evidently describing a type of animal, not a plant, and he makes no mention that they sting.
I thought that puzzle might be cleared up by a letter (with illustrations!) from Joseph Gaertner MD, which was published in the Philosophical Transactions (Vol 52, 1761) with the title ‘An Account of the Urtica Marina’, in which he writes that he “met with several new and undescribed sorts of the urticae marinae, called by Mr. Hughs the animal flowers”. Animal flowers, that sounded promising.
Dr Gaertner then notes that “the celebrated Mr. de Reaumur” has rightly observed that the name urtica “has been very improperly applied to this kind of animals; for it is certain, that not a single species of them is possessed of that stinging quality like a nettle” – but as his letter continues it seems to me that these “sea-nettles” are very different from the “globules” that Halley has encountered.
I then found A Hand-book; or, Concise Dictionary of Terms Used in the Arts and Sciences by Walter Hamilton (1825), which had this entry: “URTICA MARINA. The Sea-Nettle. In Natural History, also named the jelly-fish, and sea-blubber.”
Jelly-fish. Angus Armitage in his 1966 biography states that Halley had run into a colony of jellyfish and this statement is repeated by both Cook and Thrower, though none offers any justification for the identification.
There is, however, a jellyfish known as the Sea Nettle (Chrysaora quinquecirrha), so might that be the animal? I have to say that having watched a few online videos of these creatures, I think it unlikely.
It seems odd to me that Halley’s crew appear to be as mystified by these “globules” as Halley is – and perhaps they must remain a mystery, but if anyone does have any ideas about their identity, do please get in touch.