Did you know that the first Monday of October was World Habitat Day?

Our habitats are where we have everything that we need to live happy and successful lives. Just like humans, fish have their own habitats that provide them everything they need, including food, shelter, and essential nutrients. Some fish work together by schooling and shoaling in order to get everything they need to survive. One way to notice schooling fish is when they are swimming in the same direction to conserve energy. Shoaling fish stay together for social reasons; more specifically to find resources through foraging, protecting their territory and each other from predators, and find potential mates. There are two types of shoaling fish, optional or obligate shoalers; tuna and herring are notable shoaling fish.

With the effects of climate change and other risk factors, this makes it essential for some fish to stick together. When invasive species take control over a habitat’s natural resources, shoaling fish can work together to find food and resources. It can take the efforts of many herbivorous fish to feed on invasive species like curly-leaf pondweed, eurasian water milfoil, and algae. Similarly, when there is an excess of algae in the water that threatens coral reefs (also known “eutrophication”), the efforts of many fish can lessen these threats. 

The theme of this year's World Habitat Day is Resilient Urban Economies and was celebrated on the 2nd. In the face of our changing urban world, the threats facing fish get even bigger. We can support our resilient fish communities by shrinking our carbon footprint and doing our part in reducing the spread of invasive species into our water.

Freshwater Dolphin Day is October 24th, only a week before Halloween! After reading about freshwater dolphins, like the pink Amazon River Dolphin (Inia geoffrensis), you will surely be inspired to dress as one to trick-or-treat. 

Although most dolphins live in the salty ocean water, there are several species that inhabit freshwater systems, known as “river dolphins.” The most famous of these is the Amazon River Dolphin, or Inia geoffrensis, which is popular for its pinkish color. This species lives in the Amazon River which travels through many South American countries including Brazil, Columbia, and Peru. Amazon River Dolphins can weigh up to 350 pounds and grow up to 9 feet long! 

It is believed that Inia geoffrensis gets its pinkish color from its diet, similar to how flamingos turn pink due to eating shrimp. Shrimp contain a pigment called “carotenoid” that makes them appear pinkish, which is then passed on to the river dolphins that eat them. Other prey the Amazon River Dolphins eat include crabs, piranhas, and catfish. In fact, they have two types of teeth to help them catch different types of prey; sharp, canine-like teeth for piercing, and flat, molar-like teeth for grinding. 

Another interesting feature is the large, flexible bulge on their head called a “melon,” which assists the Amazon River Dolphins in ‘echolocation.’ Echolocation is when a dolphin locates objects in its environment by sending out sound waves and sensing how these waves reflect, or ‘bounce’ off nearby objects. This ability is also seen in saltwater dolphins, except without a melon. Unlike oceanic dolphins, which travel in large pods or “schools,” the pink Amazon River Dolphins tend to travel alone or in pairs. They are rarely seen in larger groups; the largest pod ever seen was only eight river dolphins.