mtracy's blog

The phylum Chordata contains a number of groups including, Vertebrata, Cyclostomata, Gnathostomata and so forth. There are five unifying characteristics that all chordates have at some point in their lifecycle, whether it be the embryonic, larval or adult stages. It is important to note that these do not have to be present at the same time during the organisms lifecycle. The first of these characterstics is the presence of a notochord. This is a rod that runs the length of of the body and provides a flexible yet ridged support structure. A second characteristic all Chordates have is a dorsal hallow nerve cord. This is a hallow nerve chord which runs the length of the body and, as the name suggests, sits dorsal to the notochord. Chordates also posses an iodine fixing gland. In many groups this organ is an endostyle, but it is similar to the thyroid. The last two characteristics chordates have is a post-anal tail and pharyngeal gill slits.

One example of a chordate is the Tunicate. As an adult, this blob shaped organism adheres to surfaces and filter feeds. At this stage of its life it is entirely sessile and the only chordate it possesses is its endostyle, which itself is necessary for filter feeding. However, the larval stage of the Tunicate is a small and motile organism. In this stage of life, all the traditional characteristics of a chordate are present. This demonstrates how important it is not to examine only one stage of life when organizing them into their classifications and exploring evolutionary history. Many traits are present when in development, and lost during adulthood.

The leg appendages of the spider have at least two joints where they bend. The first joint is located about 1cm up the leg. This first joint is colored somewhat darker than the rest of the spider’s body. The second leg joint is located about 1cm from the first. This joint also had a darker colored section, though it was followed by a lighter, almost translucent, section of leg. There is a likely another joint present where the leg meets the thorax, allowing for better movement of the spider.

There was a large spider in the plastic container given to me. While initially moving wildly, this quickly ceased. The spider itself has eight legs. It is light brown in color. However, the abdomen is darker in color and the largest part of the spiders body, other than its eight legs.

The spider seems too large for the small plastic container, given its long legs. Upon tapping the container, the spider began to move rapidly again, in what seemed to be a failed attempt to properly orientate itself into a proper position. (ie: to not be upsidedown). Occasionally the spider goes through spurts of rapid movement as it tried to properly orientate itself, followed by times of rest, where the spider will barely move.

The legs of the spider have two or more joints, two on the legs themselves where they bend. There are likely joints where the legs attach to the body proper as well. There is a darkened area at the first leg joints (not the possible joint that exists where the legs meet the body but the first joint on the leg itself, after 1cm or so). There may also be a somewhat darkened area, followed by a lighter or even transluent area at the second leg joint, although this is hard to see with the naked eye. There may be a joint between the thorax and abdomen of the spider, or at the very least this section has the capability of bending.

The legs of the spider are likely less than one milimeter in thickness but 2-3cm in length when fully extended. The body, from head to abdomen looks to be about 1cm in legnth and a few milimeters in thickness.Where the base of the leg touches the plastic container bends, suggesting the leg itself isnt entirely rigid. Though injury is possible.