WHO says invertebrates don’t have a sense of humour? In Hawaiian Coral
Reef Ecology, Dave Gulko brings the spineless wonders of coral reefs to
life with antics to rival the silliest sea otter or the giddiest hyena.

Symbiotic algae living inside coral polyps are an “endless supply of candy
bars in your pocket”. Coral reproduction is likened to feeling romantic, but
being superglued to your chair. A polka-dotted cartoon polyp points and
demonstrates like a game-show hostess (those dots are symbiotic algae). Many of
the bizarre symbioses of the coral reef need no embellishment. The “pom-pom”
crab carries a set of anemones on the ends of its claws, which it uses to
gingerly mop small organisms from the detritus on the reef. A tiny crab
contentedly camps out in the anus of a sea cucumber. No subject is too tedious
for Gulko’s humour, even the advantages of a colonial organism are illustrated
by a housefly as large as a jumbo jet.

Even though the main characters keep poking their tiny tentacles irresistibly
towards the reader’s funny bone, the object of Gulko’s book is serious
science—the natural history of coral polyps and their many amazing
symbionts that make up coral reef ecosystems. Gulko is taking on an enormously
important subject. Coral reefs rival tropical rainforests in productivity and
ecological complexity, and sadly are just as endangered. Some 32 per cent of the
invertebrate species in Hawaiian reefs, for example, are unique: starfish, sea
urchins, sponges, snails, worms and, of course, corals. Descriptions of these
organisms and their myriad relationships is a pressing task in the face of
environmental degradation from pollution and physical damage. That Gulko
approaches this responsibility with a smile is a shining example of constructive
environmentalism.

Gulko deals first with the corals and related animals that make up the reef
at the level of individual organisms: their physiology, structure (“a wonderful
stomach with a mouth and tentacles”) and behaviour. He includes a comprehensive
and animated guide to the species of corals common in Hawaii and their ecology.
Then he explores the use of coral colonies by other organisms for food or
shelter: “corals as condominiums”. From spaghetti worms to parasitic trematodes
to juvenile fish, the book reveals the ecology of symbiosis on a case-by-case
basis. Finally, Gulko turns to coral reefs as ecosystems, and the various forces
and interactions that mould the reef.

His three-tiered organisation is helpful, but the comprehensive nature of his
subject requires him to go off at many disorienting tangents. Describing corals
as organisms calls for a description of other members of the phylum Cnidaria to
put them in context. And no mention of anemones is complete without addressing
anemone symbioses although we have to wait many pages before a glimpse of other
reef symbiotes. The bold multimedia pages often stand out on their own like
mini-lessons on a topic. But Gulko’s overall message of the forces shaping reefs
remains compelling.

The eclectic montage of photos, diagrams, fun facts and funnies makes Gulko’s
book hard to categorise. It’s much more than a field guide, although its
species-by-species coverage of Hawaiian corals is unrivalled and would be useful
to the serious diver and amateur naturalist. It’s not quite a textbook, even
though it covers the most pressing issues in coral reef ecology with authority
and includes and “pop quizzes” to test the reader’s invertebrate smarts. It’s
too funky for a coffee table book: although the photography is excellent, many
of the computer-generated graphics of coral habitats or other topics are not
pleasing to the eye. But Hawaiian Coral Reef Ecology will hold a
special place in the hearts of naturalists and students of marine ecology for
its valuable insights, quirky style and unsinkable good humour.

Trilobites evolved into more than 1500 genera. They survived for about 300
million years, but vanished around 250 million years ago. ĐÓ°ÉÔ­´´s usually
attribute the trilobite’s demise to newly evolved predators, like fish. But why
the trilobites succumbed to these new dangers when other arthropods remained is
a mystery.

Having examined thousands of trilobite fossils found in rocks near
Cincinnati, Ohio, Danita Brandt of Michigan State University in East Lansing
says that their unusual moulting habits may have been the cause. All arthropods
moult by shedding their exoskeletons periodically so that they can grow into new
and larger ones. Modern arthropods like lobsters moult in a few minutes: a
single suture splits like a zip.

But Brandt found that trilobites had several patterns of opening. Each of the
many segments of their bodies could moult separately, taking several days. This
left their bodies vulnerable to primitive fish and squid. “Moulting is a very
dangerous time for an arthropod,” says Brandt, who will present her findings at
a meeting in Ontario next month.

Trilobites may have made a last-ditch attempt to improve the situation.
Brandt says the last trilobites tended to have fewer body segments, so that they
could moult slightly faster. “Why didn’t trilobites take the next step and
develop a consistent moulting pattern?” asks Brandt. “We may never know.”

The author of that splendid work Plant Biomechanics and Plant
Allometry gives plant evolution the full attention usually reserved for
organisms with guts and brains. Niklas throws a few bones to his zoocentric
colleagues. For instance, ferns are the amphibians of the plant world, and seeds
are the functional equivalent of amniotic eggs.

Niklas begins by reviewing the basic evolutionary principles from a botanical
perspective, and tracing the resplendent history of plant life. Then he turns to
the meat, so to speak, of the matter and his own interest in the relationship
between plant form and function. Niklas applies computer simulations to chart
hypothetical evolutionary paths through multivariable “morphospaces”.

The morphological variables chosen are necessarily simplified, and the
assumptions seem drastic at times. But the results resonate with what is known
about the history of plants and add exciting new insights to the evolutionary
debate.

Niklas relies heavily on evolutionary biologist Sewall Wright’s metaphor of a
“fitness landscape” where populations blunder through maladaptive valleys to
reach new fitness peaks. He calls his morphological simulations “adaptive walks”
over such landscapes. And although Niklas has his idiosyncrasies and opinions,
this powerful metaphor provides a balanced approach uncommon in evolutionary
debates. The landscape allows equal time to random mechanisms and natural
selection, and illustrates how evolution depends on the interaction of the
two.

The Evolutionary Biology of Plants will make an engaging text for
any course in evolution, and a valuable addition to the library of those
interested in the history of plants.

Red-winged Blackbirds: Decision-making and Reproductive Success by
Les Beletsky and Gordon Orians (University of Chicago Press, ÂŁ17.50/
$21.95, ISBN 0 226 04187 5) is the culmination of the work of two
veterans in the field. After 16 years spent recording the behaviours and
lifetime reproductive success of hundreds of tagged blackbirds, the authors can
assess models with the authority of time.

Social systems, like the polygynous system exhibited by red-winged
blackbirds, emerge from the conflicting genetic interests of the individuals in
them. Beletsky and Orians take this approach to new heights by considering the
interests of male and female blackbirds separately.

Male reproductive success follows from when, where and how they acquire
territories. Female success is determined by when and where they nest, who they
breed with, and how much energy they invest in their offspring. The sexes’ fates
are so separate that a female may choose a nesting site by the familiarity of
neighbouring territorial males, rather than the virtues of her mate.

The “decisions” of blackbirds revealed by Beletsky and Orians do not imply
that they consciously evaluate their options. The authors assume that their
responses to changes in the environment or the behaviour of other blackbirds are
determined by a genetic logarithm, and use game theory to predict how
evolutionarily stable decisions interact with these variables. But their
impressive data allows them to choose conditions where each model
excels—impossible in shorter-term studies.

Red-winged Blackbirds marks the frontier of a more mature
behavioural ecology. It will be a valuable resource for students of behaviour,
or any biologist interested in reproductive ecology.

The most direct measurement of wildlife populations would be to interview
animals in the way we do people when taking a census. Married? Occupation?
Fecundity and gestation? How much browse and how much bark? Are you a K
-strategist or r-strategist? Unfortunately, animals are no more fluent
in ecological jargon than I am in Bengal tigerese. However, all but the simplest
creatures have a repertoire of behaviours which can give us insights into their
relationship with the environment.

Imagine your own behaviour on a trek into the wilderness. Your group is
equipped and eager at the start. But after one week of rigorous hiking you have
reduced the food reserves to a fraction of your need. Food must be rationed to
miserly half-portions, resulting in shorter tempers, lower motivation levels and
selfishness. Voices would rise over the last helping of macaroni and burnt
cheese. Evidence of group erosion would be apparent in body language, hiking
distances or even physical violence—even if the numbers on your ill-fated
trip managed to remain constant.

But to be fair, the difficulty does not all lie with the number-crunchers.
Ethologists have struggled hard to characterise the behaviours of their
subjects. But it is unusual for this information to be tied in with the
population dynamics of the animals being studied. Most behaviour is recorded in
a vacuum, as if exemplary of the species at all times. But the real meaning of
behaviour only emerges when it is considered in association with population
size, density, resource use and availability. Behaviour and population ecology
are two sides of the same coin.

Wildebeest provide a striking example. These bearded ungulates spend half the
year sweeping hundreds of miles in a cyclic migration pattern throughout East
Africa. The relation between the herds and their environment is difficult to
pinpoint numerically because their environment changes with every dusty mile, as
do their numbers. In search of suitable mating grounds, the herds amble along
with the gradient of rainfall. They avoid areas where the grass is so tall that
they are easily stalked by predators, but they also avoid parched regions
awaiting rain, for ever walking an ecological tightrope.

The key to understanding this delicate balance is to recognise that the
animals are telling us about it through their behavioural consensus. Simply put,
animals on the move are hungry, while animals that remain still are probably
eating—a vote to stay for lunch. The availability of resources for
wildebeest, or any nomadic species, is demonstrated by how far they must go to
feed the masses. An intuitive ecologist could read the balance of nature in the
migration patterns of these animals. Oddly, counting would be a less direct
measure.

Another example comes from the grizzly bears of Yellowstone National Park.
Most animals are inclined to disperse when they are young, and it is generally
young animals that venture into new territory if the population is expanding.
But old bears are as common as young ones outside the Yellowstone border. It
turns out that the normal seasonal movements of grizzlies are so large that
transgressors are inevitable—whether there are 10 bears in the park or
1000. Numbers do not add up here either. Only marking and thoughtful observation
have shed the necessary light on grizzly populations.

Animals can confound even the simplest of ecological measurements if their
behaviours are not understood. For example, biologists in the US and Russia
conduct aerial censuses of walrus populations in the Bering Sea every five
years. That their results are limited and highly variable must undermine the
wisdom of using such methods. Walruses move on and off the ice floe in huge,
blubbery herds, driven perhaps by the same sort of consensus that moves
wildebeest herds. When on the ice, they can be counted—at sea, they
cannot.

These examples show how understanding behaviour can enrich the assessment of
animal populations. The missing ingredient is something qualitative rather than
quantitative. The application of behavioural observations is not a substitute
for ecological measurements, but provides a complementary perspective and a
powerful deductive tool in its own right.

As I bicycled with my wife through Mali, Burkina Faso, Ghana and Côte d’lvoire, we saw the relentless harvest of “bush meat” all around us. Men held up bloody flanks of duiker to tempt passing motorists to buy. Every busy road had its “rat man”, who killed giant rodents with a machete and hung them from a branch like Christmas decorations. Boys pelted roosting fruit bats with slingshots, and brought the membranous mammals home in their pockets for the sauce pot. Birds in particular didn’t have a snowball’s chance on the equator.

A purple heron is a splash of colour and grace on the edge of a marsh, but in the village market it was only food. We had stopped for a warm soda by the Black Volta river, in central Ghana, when we came face to face with one such heron. The man selling it had its wings and long neck clenched in one hand, making it look more like a giant purple pretzel than a living creature. I asked him why someone would buy the panting, twisted bird, and he said, “To eat it.”

It was the same story wherever we went. Two boys by the roadside in Burkina Faso held up a pair of fledgling barn owls by the tips of their wings, allowing the morning light to shine through their white primary feathers. A young man in the coastal village of Toukouzou Two paraded with a black crake under his arm, the marsh bird’s long red legs tied together and its neck limp with exhaustion. A boy in Mali’s Dogon country had tied a string to the yellow talon of a small hawk, and was swinging it around like a bola.

No bird was too small or shy to attract the interest of the hunters. We were eating breakfast by the side of the road one foggy morning when a man came by who had just shot a bulbul with his slingshot. The bird, the size of a sparrow and indistinct in its coloration, was barely big enough to fill the man’s palm. But he was obviously pleased; it had not been an easy shot. What would he do with the limp little lump of feathers? “Eat it,” he said.

We did not eat any bulbuls or barn owls that we know of. But any and all sources of animal protein were eligible for the “sauce” which accompanied the local staple, whether it was manioc in Côte d’Ivoire or millet in Mali. What disturbed me more than the prospect of finding delicate little bones in my groundnut stew was the nonchalance, one could say callousness, with which these bright bits of protein were plucked from the trees and wetlands.

Sentimentality for small creatures is one of those luxuries that, along with pure water and long lives, most West Africans have to do without. Sympathy for other animals comes from a more secure relationship with nature than most of the villagers we encountered will ever have. Families have more children than they can feed adequately. Environmental degradation and falling world prices of cash crops such as cacao, coffee and cotton make it harder each year to run a viable farm. In a region where 80 per cent of the diet is a starchy staple like manioc, protein is taken wherever it can be found. A purple heron on the edge of a reedy marsh, even if it was the last one in Ghana, would inspire less sympathy than a malnourished child.

Lest we forget, it was not long ago that Western culture took a similar view of the proper role for pretty little birds. As recently as the last century, thousands of wild larks were sold in the London poultry markets. Robins, titmice, wagtails and wrens were all fair game in parts of southern Europe. The scarcity of these birds in the wild two hundred years ago was symptomatic of their popularity on the European menu. Relative prosperity in Europe and the US in this century made most birds too insubstantial to bother with, and opened the way to a new relationship with nature. Hunting titmice became distasteful, as it is to most of us today.

West Africa is on a different trajectory. Its citizens have been at the raw end of development since Europeans began trade in its gold, ivory and human beings. Their only prosperity since then has been in population growth. Sympathy for wild birds and animals is as unpragmatic and foreign a notion as family planning sometimes seems to be.

As we biked through cleared rainforests scarred with red gullies, past millet fields with their soil hanging in the air, down village lanes with worm-bellied children and bent women, we couldn’t help thinking that it would be a long time before purple herons stimulate anything other than appetite.