We have started collecting worms again! We spent Friday, Monday and Tuesday morning at various mudflats and sandy beaches. There are one or two species of nemertean worms that can be found on the surface but most of the worms found in this habitat are living in the sand and mud (which means a lot of digging!). Finding worms can be tricky and take a lot of shoveling. Hopefully if you are lucky enough to find one, they will be intact and not split in two by the shovel head. It can be really easy to break some of the worms when trying to get them out of the sand. So instead of pulling you have to carefully break the sand away away from each worm. It is really exciting when you do find a large one. They swim through sand like it is water.
One of my favorite genus of Nemerteans live in the mudflats, the Cerebratulus. They are larger then most of the other worms and can swim like an eel. They move their head like a snake but instead of eyes they have two longitudinal slits on either side of their heads called the cerebral organ furrows. These furrows are located next to two sensory organs and it is unclear which sense they might have and are using to understand their environment. Such as if these sensory organs can detect a sense of smell, taste or of movement in the water. They move their head in a peristalsis wave that gives you the impression that they are sampling the water in their environment. These slits are deeper and more developed then some of the other species of worms. They are overall very graceful and seem to move with intent. They change color in captivity and become limp and lethargic but will usually immediately revive and explore when their water is changed with fresh sea water.
Video of the Cerebratulus head waveVideo of Cerebratulus swimming in fresh filtered sea water.
It is surprising to me the biodiversity found living in the sand and mudflats. Not only is their a variety of nemertean species but there are creatures of all shapes, sizes and colors. The biodiversity also changes quickly (within a matter of feet) from one location to the next. At first I thought all the mud and sand looked the same but after a few hours of digging your realize the subtle and no subtle changes in the sediment. Sometimes the sand and silt are dense, tightly packed and can even be slightly smelly. A shovel full might retain its shape or the sand might easily fall apart. I wonder if you sampled the sediment content vs the biodiversity if there would be any patterns.
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Rebecca OrrHi, my name is Rebecca I’m from Northern California. My major is in biological sciences. I am so excited to be working in Dr. Svetlana Maslakova’s lab and learning the protocol and procedures for completing a modern biodiversity survey. Archives
August 2021
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