Wednesday, December 22, 2010
Yesterday was the first day of winter. Let's get excited about our days getting longer! Even though we're experiencing freezing temperatures and the lowest amount of sunlight of the year there's still a fair amount of wildlife in the area. Specifically, water birds. I went to the pond yesterday and found this:
It may be a little hard to tell but those are herring gulls and mallards out on the ice. I was especially amused by this image:
A male and female mallard walking across the ice slowly and carefully. They forgot their duck boots! But among all these relatively common and well known water birds we see in New England is another.
Do you see the one I mean? Just there, in the middle of all the mallards there is a gray and black bird with a white beak. It's a coot. Coots are smaller than mallards and can be found in and around bodies of fresh water in most of North America. They appear a lot like ducks most of the time, bobbing at the surface and diving for food.
When I first started noticing the coots I thought the were ducks. But they're actually in the order of birds colloquially known as cranes containing true cranes, bustards, sunbittern and coots. Rails are technically coots. This particular coot is the North American Coot which, as I mentioned, can be found from Canada to southern US and from the east coast to California. They are omnivores and feed on plant material as well as small animals such as fish, tadpoles and insects. These birds, like many north american waterbird species, serve as an important component to freshwater ecosystems. They impose predation pressures on many aquatic animals and in turn their eggs are preyed upon by many larger animals such as raccoons (Procyon lotor) and foxes (Vulpes vulpes). Supposedly they are migratory and travel to the southern part of the country during the cold months. Either we're seeing some change in that behavior or these coots are just on a stop over from even further north.
I find coots to be especially enjoyable water birds to watch. Their small bodies are often pushed about at the surface of the water by even the smallest wake and when two coots meet they often squabble briefly, giving them a somewhat comedic personality. But they are clearly capable swimmers and divers. When they leave the water one clearly sees that they are not ducks at all, their long, lithe legs gracefully take them around the shore in search of other food sources or a place to rest. The next time you're at a pond or fresh water marsh look for these small gray and black birds.
Wednesday, December 15, 2010
The other day I was looking through images of sea turtles with a coworker when we came across one of Archelon. I described it as a "prehistoric sea turtle." I then had the thought that it's funny how we describe animals as being "prehistoric." In reality pretty much every species on earth evolved before written history which would make them all prehistoric. I'll probably keep using the term to describe "extinct" species but now I'll smile whenever I do, thinking about all those "historic" species running around.
Tuesday, December 14, 2010
This post is going to start out really sciencey but there's a reason why. So bare with me for a minute while I geek out:
In taxonomy, which is the study of the evolutionary relationships between organisms, there is a distinction made between things that we call monophyletic and paraphyletic. Monophyletic groups are those that share a common ancestor. For example: birds, as far as we can tell, are monophyletic. Structures such as the beak, feathers, etc. that make birds unique among vertebrates (again, as far as we can tell from the fossil record) did not evolve multiple times. There is only one group of birds.
Paraphyletic groups appear to be very similar but are actually groups or organisms that do not share a common ancestor that gives them that similarity (because we presume that every living thing on earth does share a common ancestor somewhere). So to follow the example, birds and bats are paraphyletic. They are the only vertebrates to achieve powered flight but their common ancestor (which goes way back to the proto-reptiles/proto-mammal anapsids) did not have powered flight.
Likewise we have two terms for structures that either are or are not produced by common ancestry: these are analogous and homologous. So my hand is homologous with a bat's wing (because both my hand and a bat's wing came from the feet of those early terrestrial vertebrates) but an insect wing and a bat's wing are analogous (because they do the same thing, allow powered flight, but did not derive from a common ancestor).
OK, still with me? No? Aw, I knew all that science was going to scare folks off. Well for those that are still reading there is a point to my inane ramblings. I have seen a fair amount of lessons based around classification that end with students sorting organisms strictly by morphology (how they look) rather than phylogeny (how they're actually related). So you get wacky groups like "things with wings" and "things that eat other animals" and so forth. This is by no means bad or wrong and is sure as heck the best thing for the real young'ins. But by the time children are in second or third grade they are developmentally capable of going further and are often really interested in stuff like dinosaurs and other animals that no longer exist.
So I encourage those of you who work with young people to strengthen your phylogenetic knowledge and the next time a student asks you if you should group a butterfly with a parrot engage them in conversation about exoskeletons and endoskeletons or segmented bodies or beaks or open and closed circulatory systems. You might think I'm crazy but I've tried similar things and it often works. We should never underestimate how much science a third grader is willing to digest.
Of course I started thinking "what is so weird about a hand-fish?" when I read through this list of National Geographic's Top 10 Weirdest New Animals of 2010 but some of these critters are pretty cool.
To keep on the worm theme, be sure to check out the polychaete in the list.
Saturday, December 11, 2010
A week or two ago I was visiting a science classroom teaching a squid dissection and the teacher had a poster on the wall that was a visual map of the different phyla in the animal kingdom. It was a really amazing poster and I tried to find out if I could order it but apparently the company that makes it only sells to retailers. So that was sad.
But the important thing is that I counted the number of phyla that were described as some kind of worm. The total count? 11. That's about a third of animal phyla.