Tastiness Protects Seeds From Beetles

a large white seed pod resembling the shape of a pea pod hangs from a tree in the sunlight with other branches blurry in the background

Biological Strategy

Wattle

AskNature Team

Image: Rotational / Wikimedia Commons / Public Domain - No restrictions

Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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Seeds of Acacia trees survive attacks by parasitic beetles by attracting herbivores whose digestive juices kill the parasites' larvae.

Image: Hans Hillewaert / Wikimedia commons /

Pods of a Camel Thorn (Acacia erioloba) at Sossusvlei, Namib desert, Namibia

Image: Rotational / Wikipedia /

Acacia erioloba fruits and foliage nr Potgietersrust, Transvaal, South Africa

“The species of acacia whose umbrella shape is so typical of the plains of East Africa encloses its seeds in small twisted pods. These are very rich in and many of the plant-eating animals on the plain relish them. Those seeds that remain uneaten on the ground seldom if ever germinate, whereas those that are swallowed with the pods do. It used to be thought that this was because stewing in digestive juices weakened the covering of the seeds and made it possible for the infant plant within to break out. The truth, however, is somewhat different. Within a few hours of the acacia tree shedding its pods, large numbers of a particular kind of small beetle fly in, pierce the pods with their sharp ovipositors and lay their eggs within. The eggs hatch rapidly and the tiny grubs then proceed to feed on the acacia’s seeds. Unless, that is, the pods are eaten by an animal such as an elephant. Although the elephant grinds up the pods with its teeth, many of the seeds remain unharmed and are swallowed with the mash. In the stomach all the beetle eggs are killed stone dead by the digestive juices. So when the seeds finally return to the outside world with the animal’s droppings, they have been freed from their insect pests by the elephant, just as effectively as seeds of wheat that have been treated by a farmer with insecticide.” (Attenborough 1995:29-30)