James L. Gould

Biogenic magnetite as a basis for magnetic field detection in animals

Bacteria, sharks, honey bees, and homing pigeons as well as other organisms seem to detect the direction of the earths magnetic field. Indirect but reproducible evidence suggests that the bees and birds can also respond to very minute changes in its intensity. The mechanisms behind this sensitivity are not known. Naturally magnetic, biologically precipitated magnetite (Fe3O4) has been found in chitons, magnetotactic bacteria, honey bees, homing pigeons, and dolphins. Its mineralization in localized areas may be associated with the ability of these animals to respond to the direction and intensity of the earths magnetic field. The presence of large numbers (approximately 10(8)) of superparamagnetic magnetite crystals in honey bees and similar numbers of single-domain magnetite grains in pigeons suggests that there may be at least two basic types of ferrimagnetic magnetoreceptive organelles. Theoretical calculations show that ferrimagnetic organs using either type of grain when integrated by the nervous system are capable of accounting for even the most extreme magnetic field sensitivities reported. Indirect evidence suggests that organic magnetite may be a common biological component, and may account for the results of numerous high field and electromagnetic experiments on animals.

Bees have magnetic remanence.

Honey bees orient to the earths magnetic field. This ability may be associated with a region of transversely oriented magnetic material in the front of the abdomen. The magnetic moment apparently develops in the pupal state and persists in the adults.

Tail size and female choice in the guppy (Poecilia reticulata)

SummaryUnder laboratory conditions, female guppies demonstrate a clear preference for males with larger tails, and this preference translates into enhanced reproductive fitness for these males. Females also prefer males with higher display rates, a behavior which appears to be linked to tail size, but which can be experimentally disassociated. This appears to be a case of female-choice sexual selection.

How Bees Remember Flower Shapes

Bees are able to learn to distinguish between flowers with different shapes or patterns. Some studies have suggested that bees remember only isolated features such as spatial frequency and line angles, rather than the photographic search images that are characteristic of vertebrates. New data indicate that this presumptive vertebrate-invertebrate dichotomy is false; bees can store flower patterns as a low-resolution eidetic image or photograph.

Landmark learning by honey bees

Abstract There are two published models for landmark learning by honey bees: (1) bees remember only the presence or absence of landmarks in each of several sectors around a food source, or (2) bees store a visual image of the landmarks. Experiments reported here indicate that bees are able to remember landmarks pictorially, and store their location, shape and colour. The angular resolution of the memory near the visual horizon is about 3·1° horizontally and about 5·5° vertically; this suggests that landmark memory has a higher resolution than the 8–10° measured for flower memory.

Pattern learning by honey bees

Abstract Honey bees learn to recognize flowers on the basis of their odour, colour, and pattern. Previous work had suggested that a flowers pattern is remembered by virtue of several abstract parameters such as spatial frequency, rather than as pictures, but the evidence was not conclusive. New experiments strongly suggest that bees can remember patterns as low-resolution pictures; the resolution is roughly 10°. Control experiments further indicate that flower learning can also involve conditioned inhibition.

Ethology and the Natural History of Learning

In the past there has been a tendency for many ethologists to dismiss laboratory studies of learning as unnatural and irrelevant, while many students of animal learning have seen little relevance in the ethological work on the innate bases of behavior. We argue and, in a preliminary way, attempt to demonstrate that a selective synthesis of these two disciplines offers a potentially powerful perspective on learning and suggests comprehensive and testable hypotheses about the mechanisms, organization, and evolution of learning in animals under natural conditions.

Bees Have Rules

Honey bees frequently dance with some view of the sky, orienting themselves to the sun or natural patterns of polarized skylight. Three new conventions have been discovered in the dance language which are used in these circumstances to eliminate potential ambiguity in the dance message.

Ethological and Comparative Perspectives on Honey Bee Learning

Ethologists are concerned with the mechanisms and evolution of behavior. They presuppose that natural selection will have acted as much on behavior as on morphology and physiology (Darwin, 1872). In consequence, some aspects of behavior are likely to be species specific, “tuned” to the contingencies of an animal’s niche. Traditional behavioristic psychologists, on the other hand, focus more narrowly on learning and emphasize species-independent behavior in their search for a general-process theory of learning. I have argued that the terminology and results from each perspective are complementary and are useful together in analyzing invertebrate learning. Studies of vertebrates can help illuminate learning in insects, and vice versa (Gould, 1986a).

Natural History of Honey Bee Learning

The life style of honey bees requires them to learn a variety of specific things in order to navigate and forage. The need for learning is sufficiently predictable with regard to the behavioral contexts and useful cues that it is highly structured and relatively easily studied. Although each cue seems to be learned independently, the set of cues memorized in each context appears to be stored as a unit. The exact nature of the storage system for flower shape, landmarks near the food, and navigational landmarks, as well as certain navigational parameters, is not yet perfectly clear. The nature of these ambiguities is explored. The possibility that some form of a synaptic selection strategy might underlie bee learning is also explored in a preliminary way.