There is considerable obscurity about the story of this ascent, although corroborated by M. JOHN. Its motive for climbing is not apparent, since water being close at hand it could not have gone for sake of the moisture contained in the fissures of the palm; nor could it be in search of food, as it lives not on fruit but on aquatic insects.[1] The descent, too, is a question of difficulty.
[Footnote 1: Kirby says that it is “in pursuit of certain crustaceans that form its food” (Bridgewater Treatise, vol i. p. 144); but I am not aware of any crustaceans in the island which ascend the palmyra or feed upon its fruit. The Birgus latro, which inhabits Mauritius, and is said to climb the coco-nut for this purpose, has not been observed in Ceylon.]
The position of its fins, and the spines on its gill-covers, might assist its journey upwards, but the same apparatus would prove anything but a facility in steadying its journey down. The probability is, as suggested by Buchanan, that the ascent which was witnessed by Daldorf was accidental, and ought not to be regarded as the habit of the animal. In Ceylon I heard of no instance of the perch ascending trees[1], but the fact is well established that both it, the pullata (a species of polyacanthus), and others, are capable of long journeys on the level ground.[2]
[Footnote 1: This assertion must be qualified by a fact stated by Mr. E.A. Layard, who mentions that on visiting one of the fishing stations on a Singhalese river, where the fish are caught in staked enclosures, as described at p. 342, and observing that the chambers were covered with netting, he asked the reason, and was told “that some of the fish climbed up the sticks and got over.”—Mag. Nat. Hist, for May 1823, p. 390-1.]
[Footnote 2: Strange accidents have more than once occurred at Ceylon arising from the habit of the native anglers; who, having neither baskets nor pockets in which to place what they catch, will seize a fish in their teeth whilst putting fresh bait on their hook. In August, 1853, a man was carried into the Pettah hospital at Colombo, having a climbing perch, which he thus attempted to hold, firmly imbedded in his throat. The spines of its dorsal fin prevented its descent, whilst those of the gill-covers equally forbade its return. It was eventually extracted by the forceps through an incision in the oesophagus, and the patient recovered. Other similar cases have proved fatal.]