Category Archives: Invertebrates

Trouble for Whales? Their Favorite Food Could Be Disappearing

What is one of the baleen whale’s favorite food? Krill. But as carbon dioxide levels rise, it creates a big problem for these tiny crustaceans.

Studies at the Australian Antarctic Division agency found that krill eggs do not hatch when exposed to higher CO2 levels. In fact, Antarctic Division biologist So Kawaguchi believes there will be a 20-70% decline in Antarctic krill populations by the year 2100 and a complete extinction by 2300. Dr. Kawaguchi says:

“Higher levels of carbon dioxide in the water mean greater levels of ocean acidification. This interrupts the physiology of krill. It stops the eggs hatching, or the larvae developing.”

Although krill are tiny creatures, they are one of the most abundant species on earth and have a massive role in the marine ecosystem. They sit at the bottom of the ocean food chain and serve as sustenance for (or sustenance for the prey of) several animals such as fish, squid, sea birds, seals and whales. If krill die off – or populations diminish significantly – it will have a serious, negative impact on baleen whales and much of the ocean’s ecosystem.

It’s not too late, however, as Kawaguchi suggests a moratorium on fishing in the region until the agency can dive deeper into the effects ocean acidification has on krill.

Featured image by Jerry Kirkhart / CC BY 2.0


Cold-Blooded Animals Will Probably Struggle With Climate Change

As the planet warms, cold-blooded animals will have trouble adjusting. According to a study by two biologists, cold-blooded animals, which cannot regulate their internal temperatures, will struggle with climate change.

The biologists, Alex R. Gunderson and Jonathon H. Stillman from the University of California, Berkeley and San Francisco State University, analyzed 230 cold-blooded species from 112 published studies on plasticity – or the ability of animals to modify their thermal tolerance when they experience new environmental temperatures. They found that cold-blooded animals have an particularly tough time adjusting and that on average most aren’t flexible to warming climate changes.

Gunderson states:

“Overall, we found that even though all of the animals have some plasticity, they all have relatively low levels of plasticity. As environmental temperatures rise due to global warming, the animals will get closer and closer to their thermal limits, and plasticity won’t do much to help them.”

Gunderson and Stillman discovered that the plasticity of animals differs based on their habitat. So cold-blooded species like lizards and insects have less plasticity than fish and crustaceans, and thus will have a more difficult time surviving in the changing climate. Gunderson explains:

“The difference between terrestrial and aquatic animals is that the aquatic ones have a higher capacity to adjust, but it is still relatively low. Ideally, if temperatures went up three degrees, the animals’ tolerance would go up three degrees as well. But that’s not what we see.”

The study’s analysis suggests that certain animals – such as lizards, insects and snakes – can’t depend on plasticity. Rather, they will have to rely on behavior modifications, like moving to greater altitudes or more shaded habitats. But unfortunately, not all animals live in regions where such behavioral adaptations are feasible and in those cases, the species will have to evolve higher tolerance for the heat in order to survive.

Featured image by Mark Fischer / CC BY-SA 2.0