Tuesday, April 22, 2014

Ben LaBelle's Internship, Spring 2014 - Part 5

Hello everyone,

This is Ben from the sorting lab again. Today, I would like to take you on a quick run through of sorting a sample and show you some of the major groups we find in our samples. First, we rinse the stained sample and place it into a sorting dish so we can start sorting through the sediment, shells and other debris.
As I come across organisms, I like to place them into a small dish of ethanol so I can come back to them later and view them clearly for ID. It’s surprising how much better you can see fine detail when you do not have to look around all the sediment and left over stain floating around in the sample dish.

Nematodes are some of the most common, and usually smallest, organisms we encounter in our samples. These small, simple worms are mostly deposit feeders and ingest large amounts of sediment in their hunt for food.
The next group we encounter in almost every sample are the polychaetes. These segmented worms have a wide range of feeding strategies, including deposit feeding, suspension feeding and predation. Here you can see one next to an empty gastropod shell.
Harpacticoid copepods are another common group found in our samples, though not nearly as common as the nematodes or polychaetes. These small benthic crustaceans are typically distinguished by their antennae.
Another common crustacean group found in our samples are ostracodes. These are sometimes difficult to distinguish from bivalve mollusks due to the similar shell structure, but you can usually see antennae sticking out of the shell, or hair like projections like this specimen below to help sort them out.
Tanaids, another crustacean group, are often found in our samples. These small shrimp like creatures are relatively common in the deep ocean sediments and can most easily be identified by their pair of large claws.
Aplacophorans are a semi-common feature in our samples. These primitive mollusks are almost exclusively found in deep water and are fairly easy to recognize in samples because of their pearlescent sheen.
Intact scaphopods, or tusk shells, are a rare occurrence in our samples. The shells of these deposit feeding mollusks are often seen, but a live-on-collection specimen only occurs in a small fraction of samples.
The last group I found represented in this particular sample was the ophuroids. Ophuroids, or serpent stars, are another rare occurrence in our samples. These organisms are common in the deep sea, though many are far too large to be represented in our multi-corer samples. Small specimens like this one, or more often, pieces of the arms, are occasionally found however.
Here we have all the organisms from this particular sample in the dish of ethanol, ready to be ID’d and put into vials for family level ID by Arvind.
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Ben LaBelle, Florida State University

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