Optimizing Size Aids Survival

close up photograph of gray sea barnacles

Biological Strategy

Sessile barnacles

AskNature Team

Image: Meli1670 / Pixabay / Public Domain - No restrictions

Optimize Shape/Materials

Resources are limited and the simple act of retaining them requires resources, especially energy. Living systems must constantly balance the value of resources obtained with the costs of resources expended; failure to do so can result in death or prevent reproduction. Living systems therefore optimize, rather than maximize, resource use. Optimizing shape ultimately optimizes materials and energy. An example of such optimization can be seen in the dolphin’s body shape. It’s streamlined to reduce drag in the water due to an optimal ratio of length to diameter, as well as features on its surface that lie flat, reducing turbulence.

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Cooperate Within the Same Species

A species is a group of organisms capable of breeding to produce fertile offspring. When individuals within a species undertake activities that benefit one another, that cooperation benefits not just the individuals, but also local and wider populations of that species. Collaborating in activities such as finding food, controlling parasites, and protecting from predators enhances overall survival. To cooperate, there must be enough benefit to an individual, and especially to a population, to justify any risk taken by individuals. Through cooperation, risk is distributed among individuals and the benefits to the community are greater than the sum of the benefits to individuals. An example is birds that gather in flocks, a cooperative activity more beneficial than acting alone. While some birds forage, others watch for predators. When one finds food, others also feed on it. Despite potential short-term competition for an individual that finds food, over the long-term, that same individual benefits when others find different food sources.

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Crustaceans

Subphylum Crustacea (“crust”): Crabs, barnacles, shrimp, pillbugs

Some crustaceans, like pillpugs and woodlice, live on land, but most are found in the ocean. Their heads are distinctive among the arthropods: they have two pairs of antennae and three pairs of feeding appendages that help them hold and crunch food. Crustaceans also have a unique larval stage called the nauplius (named after the son of Poseidon) which has three pairs of legs and one eye. Most crustaceans are in class Malacostraca, which contains a wide range of species that live in mostly marine environments, like krill, lobster, and mantis shrimp.

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Populations of sessile barnacles optimize space where physical habitat is limited by decreasing the average mass of an individual barnacle as population density increases.

“Space optimization is a concern for a number of creatures, particularly in situations where physical habitat is limited. In these situations, members of a population optimize space utilization depending on population size. The resulting pattern of space use reflects competitive and cooperative processes that are more complex than optimization patterns due to material or energy resource efficiency alone, as seen in many of our previous examples. The patterns of space utilization in colonial organisms are not as regular as those seen in the Fibonacci sequences, hexagons, or other examples presented herein, and therefore are not studied in the same contexts. Some trends, however, have been noted, particularly with regards to the relationship of individual mass to the population density—primarily, as density increases in a space limited environment the average mass of the individual decreases. Interestingly, for a wide variety of species, including barnacles, this relationship is close to the exponential constant of –3/2.” (Biomimicry Guild unpublished report)

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