An indicator species is an organism whose presence, absence or abundance reflects a specific environmental condition. Indicator species can signal a change in the biological condition of a particular ecosystem, and thus may be used as a proxy to diagnose the health of an ecosystem. For example, plants or lichens sensitive to heavy metals or acids in precipitation may be indicators of air pollution. Indicator species can also reflect a unique set of environmental qualities or characteristics found in a specific place, such as a unique microclimate.
Above: Burrowing Mayfly, a clean water indicator species. Since they are very sensitive to pollution, their presence is indicative of clean water.
Since their introduction to the Atlantic Ocean in the 1980s, Pacific red lionfish (Pterois volitans) have gobbled up native Caribbean and western Atlantic reef fishes, reducing their abundance by up to 90%. Researchers think one of the secrets to the lionfish’s success is a predation strategy unheard of in other fish predators—blowing jets of water while approaching prey to disorient them. The squirting water (seen in the video) overwhelms the target’s lateral line, part of a fish’s nervous system that detects vibrations and warns of approaching objects, the team reports this week in Marine Ecology Progress Series. Prey often end up facing the hungry lionfish, increasing the chances of head-first strikes and lowering the risk of the lionfish getting stuck by backwards-facing spines.
You can watch a video of the phenomena by clicking the source (wouldn’t let me embed).
When It Comes To Survival Of The Fittest, Stress Is A Good Thing
In a study led by Michigan State University (MSU) and the University of Guelph (Canada), researchers showed for the first time how females use social cues to correctly prepare their offspring for life outside the nest. The results, published in the current issue of Science, confirm that red squirrel mothers boosted stress hormone production during pregnancy, which increased the size and the chances of survival of their pups.
"Natural selection favors faster-growing offspring, and female red squirrels react accordingly to increase their pups’ chances of survival," said Ben Dantzer, formerly with MSU’s zoology department and now a postdoctoral researcher at the University of Cambridge (United Kingdom). "Surprisingly, squirrels could produce these faster growing offspring even though they didn’t have access to additional food resources."
Types of Symbiosis
Symbiosis is the close and often long-term interaction between two or more different biological species.
- Mutualism: any relationship between individuals of different species where both individuals benefit.
- Endosymbiosis: any symbiotic relationship in which one symbiont lives within the tissues of the other, either within the cells or extracellularly.
- Commensalism: a relationship between two living organisms where one benefits and the other is not significantly harmed or helped.
- Parasitism: a relationship in which one member of the association benefits while the other is harmed.
- Amensalism: the type of relationship that exists where one species is inhibited or completely obliterated and one is unaffected.
- Synnecrosis: a rare type of symbiosis in which the interaction between species is detrimental to both organisms involved.
Above: In a symbiotic mutualistic relationship, the clownfish feeds on small invertebrates that otherwise have potential to harm the sea anemone, and the fecal matter from the clownfish provides nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone’s stinging cells, to which the clownfish is immune.
Scientists Use DNA to Quickly Unravel Relationship Between Plants and Insects
Studying the relationship between plants and the insects that feed on them is an arduous task, as it must be done through direct observation. It can take years for a researcher to fully understand the diets of a community of herbivorous insects in a tropical rain forest. Now, five Smithsonian scientists are paving a fast track using the DNA found inside the insects’ stomachs, potentially turning years of research into months. This method will help scientists understand the ecology and evolution of plant-herbivore interactions more efficiently.
A Quick Introduction
The term “ecology” was coined by the German zoologist, Ernst Haeckel, in 1866 to describe the “economies” of living forms. The theoretical practice of ecology consists, by and large, of the construction of models of the interaction of living systems with their environment (including other living systems). These models are then tested in the laboratory and the field. (Field-work in ecology also consists of data collection that need not be inspired by any theory.)
A huddle of starfish adds a splash of color to the Olympic Coast National Marine Sanctuary in Washington State. The Sanctuary protects 2,408 square nautical miles off the coast, the size of Delaware and Rhode Island combined. Living in this protected area are organisms ranging from microscopic plankton to sea otters to albatross to migrating gray whales. It’s a high-nutrient environment, which is why intertidal species like these starfish thrive.
This is not a spider. Nor is it a spit wad target or a child’s miscalculated attempt at a paper mâché skeleton. This spider-shaped mass is actually a clever decoy. The inch-long assemblage of leaves, twigs, and dead bugs was meticulously arranged by a spider less than a quarter its size. The arachnid artist created this body double on his web in the Peruvian Amazon, and lurks on the strands above it, pulling strings to make the puppet move.
Biologist Phil Torres recently discovered the spider and suggests in a blog entry that its behavior is an elaborate defense mechanism that encourages predators to attack the bigger, flashier spider rather than its sneaky creator.
Such strategic distractions are characteristic of spiders in the genus Cyclosa, butother species build blob-shaped constructions which lack legs altogether. And the decoys certainly don’t move. Scientists are thus suggesting that this spider is a new Cyclosa species. Definitive identification studies are on hold until January when researchers can get a permit to actually collect the spiders and take a closer look.
Pictured above is the Salto Grande waterfall in the Torres del Paine National Park, Chile. The park features towering mountains, glaciers, lakes and river valleys and is home to diverse wildlife including rheas, condors, pumas and guanacos. The park is part of UNESCO’s Biosphere Reserve system, whose sites are established by countries and recognized under UNESCO’s Man and the Biosphere Program to promote sustainable development based on local community efforts and sound science.