Monarch caterpillars molt (shed their skin) five times throughout their larval stage. The "skin" that is left behind is actually the caterpillar's exoskeleton. An insect's skeleton is on the outside, as opposed to on the instead like mammals, fish, reptiles, amphibians and birds. Endoskeletons provide support inside the body in the form of bones and cartilage, whereas As caterpillars grow, their exoskeleton gets too tight, so they need to shed it in order to continue to grow. Each molt results in a new "instar" stage. Therefore, when the egg hatches, that tiny 2 mm caterpillar is in its first instar stage.
It will molt three more times and grow exponentially over a couple of weeks. Each stage lasts 3-5 days. The fifth and final molt is when the fifth instar caterpillar becomes a chrysalis.
Threatened & Endangered Species
There are over 1400 threatened or endangered vertebrates and invertebrates in the United States today. The difference between "threatened" and "endangered" species is that threatened species are likely to become endangered within the foreseeable future throughout all or a significant portion of its range, while endangered species are those that have become so rare that they are in danger of becoming extinct. There is no coming back from extinction. Once it's gone, it's gone...
You may not notice them in your everyday life, but with a little research and a trip or two out into the natural world, you may be able to spot a threatened or endangered species. Seeking out and actually finding a rare species is both exciting and a bit sad. Because of humans, many of these species are teetering on the brink of extinction. It is vitally important that we do everything we can to protect and conserve species at risk, so they are not lost forever.
Below are just a few examples of threatened and endangered species in North America. The main reason many of these species are listed is due to habitat loss. Click images for species and status and visit the Environmental Conservation Online Status (ECOS) website for more species.
Now for Some GOOD News!
Due to amazing conservation efforts, there are many threatened and endangered species success stories that give us hope that we can bring back at least some of the imperiled species. If we work quickly, and enough people become engaged and support conservation efforts, it is possible. Below are a few of those species! Also check out the ECOS delisted species database for more info. Click on images for species and delisted dates.
