The Marine Biological Collector
by the late John Barker (1934 - 1998)

The first question I am often asked is: what is a marine collector?
 I think this is best described by the Nobel prize winning author John Steinbeck when writing about Ed 'Doc' Ricketts of Cannery Row fame in which he wrote 'commercial fishermen harvest the sea to feed men's bodies and a marine collector harvests the sea to feed men's minds'.

Modern Developments

In the last 36 years I have worked the seas for a living, the greatest advance I have seen in practical marine biological education has been the development of the new technology for maintaining marine aquaria, including synthetic seawater, silicon sealing cement for sticking glass tanks together and improvements in the air pumps and powerheads and filtration systems.  This has enabled marine aquaria to become established in classrooms and research laboratories.
Wet Thumb (Marine Aquaria)
 Before this, marine researchers had to go to places like Millport Biological Station Isle of Cumbrae, and Plymouth Aquarium to observe and research on living marine specimens. Teachers and students were left with the prospect of observing a preserved lump of jelly, which once was a beautiful sea anemone.
 Fortunately, this is a thing of the past, and it is now possible to enjoy the pulsating beauty of our seas and estuaries in your own home or laboratory.

Career Start

I started diving in 1958 to study fish in their own environment. At that time, the only diving equipment available was government-surplus. My first two air bottles were 25 cubic feet each (we called them 'tadpoles') and came from a Wellington bomber from World War II.
 On the plus side, most of the sea bed, rocks and wrecks had never before been seen by human eyes. I was on call to recover lost nets, pots and anchors, and this was lucky for me as well as the local fishermen. The partnership that developed was to help a great deal in my collecting in the following years.

Aquarium Supply

My very first order came from London Zoo Aquarium. It was for live shore crabs to feed their Octopuses, Octopus vulgaris. The octopuses came from Jersey, and because of their short life span were renewed from the Channel Islands every year.
 Brighton Aquarium placed further orders for live specimens to fill their many large tanks; beginning an association that I maintained for many years. In 1960, I was approached by a large biological supply house for a list of specimens I could supply. Their catalogue at the time consisted of marine specimens that were normally discarded by commercial fishermen as 'trash' and shovelled back into the sea. However, not all specimens could be obtained this way, and orders from specialist researchers were passed on to me. These orders were an opening to many wonderful people who drew me into their experiments and were instrumental in showing me the beautiful life that could be seen under a microscope.


All marine collection is subject to winds, temperature and tides. The sea does not give up its secrets easily; days, weeks and even months of searching rock pools and mud flats, and making trips on fishing boats only makes me aware that there is still much to learn.
 In the 1960's the Nuffield Foundation chose the animal subjects that  were part of the studies under the school curriculum. On the list of subjects covered was cell embryology. A few of the common marine invertebrate species were ideal for the job as the eggs and sperm were large enough to be observed under a low powered microscope. The Common Starfish, Asterias rubens, was one of these. They were an abundant pest and could be obtained in large enough numbers reasonably easily. One problem was they only produced sperm and eggs in the early spring.


However, the small Keelworm, Pomatoceros triqueter, could produce sperm and eggs throughout the year. Male and female could easily be identified by the colour of the abdomen, which is yellow in the male and violet in the female. This worm lives in a 3-4 mm wide white calcareous (limy) tube and displays feeding tentacles that can be seen through a hand lens. A separate shore and shallow water species Pomatoceros lamarcki has now been identified. These worms became a weekly order, and are still used in some universities.
  Parasitic Barnacles

In the early 1970s the Parasitic Barnacle, Sacculina carcini, was used as part of a G.C.E. 'A' Level examination course. This barnacle was of interest because its life cycle involves sending out branching roots throughout the crab's body, altering the sexual character: the males develop secondary female characteristics, and presence of the parasite prevents moulting (ecdysis). The parasite looks like a yellow blob in the place under the abdominal flap where the eggs would be carried.

There are numerous other rhizocephalan barnacles parasiticising other crustaceans, notably a species called Clistosaccus paguri infecting the Common Hermit Crab, Pagurus bernhardus, the genus Peltogaster infecting other hermit crabs and Drepanorchis neglecta, that infects spider crabs.
Discussion Link
European Rhizocephalan Species List
Discussion Link 2
Discussion Link 3
Sacculina notes (from Crust-L)

Obelia Hydroids

The following year for the same 'A' level examination the specimen picked was the Obelia hydroid, which is one of our most beautiful animals, although the inexperienced layman could mistake it for a plant. Their miniature white stolons creep over the surface of the kelp fronds and other brown seaweeds, with stems and branches bearing the anemone-like feeding polyps that need to be viewed under a hand lens.

Brown Shrimps

About this time I started supplying live specimens for government agencies engaged in research into marine pollution around our coasts. The principal specimen wanted was the abundant Brown Shrimp, Crangon crangon, which was also used by both B.P. and Shell in their studies into the effects of gas embolism on North Sea divers.

 Early in 1971, I received an urgent telephone call from the British Industrial Biological Institute in Surrey; I was asked for 2000 shrimps to be delivered in less than 24 hours, and they were prepared to send a car to collect them. The Institute wanted to test the shrimps in water samples taken from the ill-fated tanker 'Pacific Glory' that had run aground in the English Channel, for the Government Agency who wanted the results in one week. Luckily, at the time I was collecting shrimps for a fish market, so I was able to supply them in time.


Collecting is only part of the story. It is essential that specimens arrive alive and in  good condition. Plastic bags and supplementary oxygen are used, but each transportation project needs to be thought out initially. Without any bad luck, specimens will arrive safely.
 So when you sit for an examination or biology lesson and look into a Petri dish full of live plankton or living worm cells, you can be sure that a marine collector made this possible.

Further Reading

The Log from the Sea of Cortez  by John Steinbeck

'It is usually found that only the little stuffy men object to what is called "popularization" of which they mean writing with a clarity understandable to one not familiar with the tricks and codes of the cult' (Chapter 10).

'It is difficult when watching the little beasts, not to trace human parallels. The greatest danger to a speculative biologist is an analogy. It is a pitfall to be avoided - the industry of a bee, the villainy of a snake .' (Chapter 11).

Biologist, April 1993, Vol. 14  No. 2, page 62.
Feature on Ed "Doc" Ricketts by J Humphreys.

An Introduction to the Biology of British Littoral Barnacles  by P. S. Rainbow, 1984.
Field Studies Council  Offprint No. 161  Vol. 6  No. 1.

John Barker Obituary  (includes links to other articles)

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