The study of fossils helps in pinpointing the extinction risks faced by ocean animals. Researchers have found a clue through the study of marine fossils ,why some animals of the ocean are more likely to get extinct than others.
An analysis that cumulatively put together fossil data of nearly 500 million years for sea or ocean invertebrates has shown that those that are mostly affected are animals of the ocean whose geographical ranges are small. This, the study reveals affects ocean animals even when their population is large.
The Earth’s surface is 70% water. This implies that any research that is done at sea has more challenges than that done on land because of the difficulties of data collection. This explains why very little is known about the status of conservation of animals of the ocean.
However, by focusing on the study of records of fossils, to understand how ocean animals got extinct in the past, researchers may very well establish how a particular species may behave in the future if the patterns observed in the records of the fossils are maintained.
Studies suggest that if patterns observed on the fossil records still hold today for species that are still alive, then the risk of extinction is much higher for species that have large populations but have a small range.
Researchers have for a long time assumed that those animals that are classified as rare are the ones that are most likely to become extinct. But there is debate on the exact meaning of the word due to the multiplicity of meanings that it can attract. The context that researchers use it refers to species of ocean animals that exist in geographical ranges that are restricted and whose populations are also small or can only withstand habitats that are limited.
For instance, although false killer whales can be found in oceans around the world, they are classified as rare because their numbers are not high. On the other hand, the species of penguins that is referred to as Erect crested although averagely abundant in its habitat in the islands that lie off the coast of New Zealand, is classified as rare because they are geographically restricted to their habitat.
Paul Harnik of the Center of National Evolutionary Synthesis, Stanford University’s Paul Payne and Carl Simpson of Berlin’s Naturkunde Museum set out to establish the unique aspects that determine what makes other species survive and others become extinct.
According to Paul Harnik, the veracity of the relationships discussed above can only confirmed through the fossil record where extinction records are documented on a long term basis. The researchers therefore examined a database of fossils of ocean invertebrates that lived in the world’s oceans from about 500 million years to the present day. The fossils that were examined were from species of sea urchins, corals, scallops, clams, snails, sand dollars, oysters, brachiopods and other sea animals. After careful examination, the researchers concluded that the major reason for the extinction of marine animals was the size of the geographical range. The area where these animals lived played a role that was only secondary in determining their survival rate. They also concluded that the animals population size did not affect their chances of survival.
In their findings, the researchers concluded that marine animals that had a combination of geographical ranges that were small and limited suites of habitats were more likely to die out than other common animals by more than six times. They went further and concluded that environmental changes do not necessarily affect individuals or areas equally in the same manner or in the same way. This confirms that a percentage of a species range would survive if something adverse was to happen to it. It was widely believed that life in the ocean was not largely affected by extinction as compared to that on land. But the situation is rapidly changing due to factors that are attributed to environmental degradation.
Paul Harnik says that their findings don’t mean that there should be no cause for worry when the population of species dwindle, rather, it is an indicator that when the range size is reduced and the habitat damaged or degraded, then the risks of extinction also increase even if species populations still remain high. The results of this research will be published in the royal B journal this week.