Leeds Studies in English: n.s. 25, (1994), 29-68
In the second book of his Life of Columba abbot Adomnan of Iona relates some details regarding the second and third voyages of the monk Cormac in search of ‘a desert place in the ocean’. During the course of his third voyage, Cormac’s curach is driven into unexplored northerly latitudes where the fragile skin-covered vessel is assailed by a swarm of small but very aggressive marine animals: ‘Quae, ut hi qui inerant ibidem postea narrarunt, prope magnitudine ranarum aculeis permolestae non tamen uolatiles sed natatiles erant’ [As those that were present there related afterwards, these creatures were about the size of frogs, very injurious by reason of their stings, but they did not fly, they swam]. The aculei with which these mysterious creatures are equipped appear to be frontal spines or projections of some sort, and Adomnan’s reference to their lack of the power of flight suggests a comparison with the beaks of birds.
Adomnan’s English contemporary Aldhelm, in his riddle on the pond-skater or water-strider, Tippula’ (no. 38), presents a creature that although unable to swim, can cross expanses of water (as well as land) on its four feet:
Pergo super latices plantis suffulta quaternis Nee tamen in limphas uereor quod mergar aquosas, Sed pariter terras et flumina calco pedestris; Nee natura sinit celerem natare per amnem, Pontibus aut ratibus fluuios transire feroces; Quin potius pedibus gradior super aequora siccis. [I walk on the waters borne up by my four feet, yet I do not fear that I shall drown in the watery main. Rather, I tread on foot equally on land and sea. Nature does not allow me to swim in the fast-moving beck nor to cross turbulent streams by bridge or by boat; instead, I walk with dry feet over still waters.]