Until yesterday I was unaware of these tiny organisms that I found in a trawl with my plankton net in the Georgia Strait between Vancouver Island and the mainland. Looking at them under the microscope, at first I thought that they were very young fish but experts in microscopic life made a positive identification as being Oikopleura sp.
They are urochardates known as larvaceans, related to the tunicates (sea squirts). Although they are technically invertebrates they have a body plan that resembles a fish with a backbone. These animals have one of the smallest DNA genome sequences of any animal. They live a very short lifespan of only a few days. They release eggs and sperm into the ocean to reproduce. Living only a few days they can appear in large numbers becoming an important component of the food chain.
This example was squeezed out of the water drop when I lowered the cover slip onto the glass microscope slide. It is laying alongside the edge of the glass cover slip and I just happened to notice it when I was scanning the slide for interesting targets.
They carry captured debris in tiny nets which, when they get clogged, are abandoned and eventually sink to the bottom. Carrying remnants of their food (bacteria and phytoplankton) this moves the Carbon from the atmosphere sequestered by phytoplankton as biomass back into the chemical form. In the process they become an important food source for larger organisms. These ‘nets’ are a significant portion of the ‘white snow’ that is observed in the water column slowly sinking to the ocean bottom.
A couple of days ago I used my plankton net and found this marine water mite in the trawl sample. I have not seen one of these before. I don’t know if they have been present but unnoticed in my samples or if it has just appeared.
This organism is closely related to the much more common and numerous freshwater relatives found in ponds and streams. The scientific literature on this species is not easy to find on the internet. I believe that it is from the family Pontarchachnidae which is the only family of the Hydrachnidae occurring in the marine environment.
Michael W. Konrad published a highly illustrated book of the marine plants and animals that can be found clinging to docks, floats, and pilings on the Pacific coast. The book surveys many organisms that are easily visible to the naked eye but to the joy of the micro-naturalist he also includes the microscopic world.
I highly recommend it to west coastal micro-naturalists. It is competently written, very informative and well illustrated. Many of the organisms will be encountered on field trips and some are suitable for viewing under a microscope. It makes good general reading on the subject.
The book was published in 2013 by Science Is Art at Sausilito CA. ISBN 978-0-9832590-0-8 paper bound. The author is Michael W. Konrad. It should still be available from book sellers online.
Foraminifera are simple organisms which, when alive, protrude pseudopodia through tiny pores in a rigid calcareous test or shell. This shell can be a single chamber or can be composed of multiple chambers. Most are marine, and can be either bottom-dwelling or floating plankton.
The accumulations of their dead shells become part of the sediment column on the bottom of the ocean. Under the microscope these shells are intricate and beautiful. They tell the story of the conditions under which they lived. They are not easy to locate in our area – but turn up as micro-fossils in sediment on the sea floor.
The shells are particularly beautiful and intricate. Each species can be identified from particular features produced in this structure. Mainly marine, both benthic (bottom dwelling) and planktonic (floating in the water column). They are little known to amateur micro-naturalists. Once they are discovered, they create a fascination which is hard to shake.
Close proximity to the sea provides many opportunities for the Micro-Naturalist to enjoy endless viewing of spectacular subjects. Plankton is one of those topics.
How to do it?
I use a small student-grade plankton net launched by hand from the shore on a line to gather samples. I view them while the subjects are still fresh. By capturing images of the most interesting subjects I was able to research and identify the organisms from reference texts.
Where to get them?
The waters around Vancouver Island BC are easy sources of phytoplankton and zooplankton. With very little effort you can get fantastic forms of microscopic life into view. Even the sand is worth studying. But you could find them in a lake, a pond or pool.
The variety and quantity of organisms is different each time. There are examples of both phytoplankton and zooplankton in the samples. Care in handling the raw sample ensures that few of the organisms are damaged and of course only a small drop of water from the sample is examined at any one time (so the sample does not need to be very large).
Identification of Organisms
I refer organisms that I cannot identify to the Amateur Microscopy Facebook group where experts assist with identification down to the genus, and sometimes even to the species level. By keeping a lab notebook I keep records of the organisms I encounter, and make notes when they are identified. This provides a reference for later use when examples of the organisms are encountered again.