STRUCTURE AND FUNCTION IN WHALE EARS

ABSTRACT

Ultrasonic echolocation abilities are well documented in several dolphin species, but hearing characteristics are unknown for most whales. Vocalization data suggest whale hearing spans infra- to ultrasonic ranges. This paper presents an overview of whale ear anatomy and analyzes 1) how whale ears are adapted for underwater hearing and 2) how inner ear differences relate to different hearing capacities among whales.

Whales have adaptations for rapid, deep diving and long submersion; e.g., broad- bore Eustachian tubes, no pinnae, and no air-filled external canals, that impact sound reception. In odontocetes, two soft tissue channels conduct sound to the ear. In mysticetes, bone and soft tissue conduction are likely. The middle ear is air-filled but has an extensible mucosa. Cochlear structures are hypertrophied and vestibular components are reduced. Auditory ganglion cell densities are double land mammal averages (2000–4000/mm). Basilar membrane lengths range 20–70 mm; gradients are larger than in terrestrial mammals. Odontocetes have 20–60% bony membrane support and basal ratios >0.6, consistent with hearing >150 kHz. Mysticetes have apical ratios <0.002 and no bony lateral support, implying acute infrasonic hearing. Cochlear hypertrophy may be adaptive for high background noise. Vestibular loss is consistent with cervical fusion. Exceptionally high auditory fiber counts suggest both mysticetes and odontocetes have ears “wired” for more complex signal processing mechanisms than most land mammals.     

BENZYLADENINE EFFFCTS ON BEAN LEAF GROWTH AND SENESCENCE

Experiments concerning the effects of benzyladenine applications on the growth and senescence of leaves have been carried out with cuttings of bean seedlings. By measuring the interactions between leaves, it was found that this kinin not only can stimulate the growth of a treated whole leaf, but it can bring about the inhibition of growth in other untreated leaves on the same plant. Consistent, with the apparent mobilizing actions of this chemical, it was found that applications to one or more leaves would induce the senescence of untreated leaves in a manner similar to the senescence-inducing effects of stem apices and flowers and fruits. The experiments suggest that the mobilization effects due to natural kinins in such centers in the intact plant may provide endogenous stimuli of leaf senescence.     

AGENCY, PERSONHOOD AND THE 'I' OF DISCOURSE IN THE PACIFIC AND BEYOND

Sahlins bases his account of Polynesian 'heroic history' partly on the fact that chiefs used the pronoun 'I' in reference to their whole group. Mosko (1992) argues that Sahlins's consequent emphasis on 'encompassment' as the modality of chiefly action is diametrically opposed to Strathern's on 'partibility', the effacement of parts of the person as a condition of action. Drawing on comparative material from the New Guinea Highlands, where big men also use 'I' for their whole group, and on Benveniste's and Urban's accounts of the meaning and use of personal pronouns, I argue instead that moments of both encompassment and partibility are inherent in language, corresponding to two distinct dimensions in which the pronouns are meaningful (the 'direct indexical' and the 'anaphoric'), and that close attention to the interaction between the two can yield new insights into the nature of personhood and social agency.