Marine Biology & Oceanography

Posted by John Blatchford

In my article ‘Collecting Olive Shells’ I have suggested that distribution data and information about species variability in any location should be published somewhere – so that others can access it.



Distribution Data

Amateur collectors are in an ideal position to amass data about the distribution of the species that interest them. In a sense any data about marine mollusc distribution is useful, but those who specialise in a particular group (be it the olives, cones, cowries, or whatever) are likely to have a more complete picture. Best of all is the information that comes from individuals who specialise in a single (or few) species.

Knowing the current range of any particular species gives a ‘base-line’ against which future changes can be measured. The effects of habitat loss, pollution and global warming will have something to be measured against.



Variability Data

For shells which show a lot of individual variation within the species it is very useful to know which forms are found where. This sort of data can help untangle the thorny problem of ‘what is each variety adapted to’, and can even help elucidate some of the tantalising questions about speciation. In the absence of detailed genetic information the way in which populations vary across their range can be very instructive.



Where to Publish

I have started a discussion where people who have already published their data, or are about to do so, can help those who are considering it.

Posted by John Blatchford

Ever since I did some of the editorial research for Pete Dance’s ‘Encyclopedia of Shells’ (back in 1973) I have been fascinated by the cowries. I have my own small collection – all of them obtained from unwanted museum specimens (which means that someone else bears the responsibility for any environmental damage!).



Scientific Value

More serious collectors, who actually travel around and find their own specimens, can add much to scientific knowledge. This is particularly true when we are looking at the distribution of any species, but it will also be useful in the future by providing a sort of ‘base-line’. Future changes in distribution (say as a result of global warming or habitat damage) will have a point of comparison. For this to be of any use it is important that each shell is individually labelled (or recorded somehow) for both date and location of capture.



Aesthetic and Commercial Value

I find shells beautiful, particularly the cowries. When they are displayed appropriately they can become almost ‘works of art’. Some of the rarer shells can also be quite expensive. I was once lucky enough to handle a 200 year old Cypraea aurantium in the Natural History Museum (London) which had attained its famous golden sheen. This specimen must be almost priceless! Not only of value to collectors – cowries (particularly C. moneta) have actually been used as currency in the past.

Posted by John Blatchford

Many strange animals are kept as pets. Some have become domesticated over thousands of years, while others are taken from the wild.

Domestic Animals

• Dogs certainly thrive when they are kept as pets, and provided they are well treated there is no cruelty involved – they simply adopt their human family and become part of the pack.
• Cats are different! They seem to retain their independence and simply treat their human associates and their houses as conveniences – being given regular food and a warm place to stay allows them pursue their own interests from a comfortable base.
• Horses do not seem to mind being used as transport, and after centuries of working with them their physical needs can be well anticipated and catered for. Keeping them does not seem to be cruel.

Wild Animals

How much cruelty is involved depends on two factors, how the animals are fed and housed, and how intelligent they are. It is difficult to imagine ways in which a pet insect might suffer – we do not credit them with much intelligence, and assume they have no self-awareness. Intelligent animals (such as the Chimpanzees and Killer Whales) are certainly aware of themselves and can suffer pain and feel emotions. Keeping any of the Great Apes or Whales in captivity can easily become cruel – they need to be with other members of their own species and to have enough space to behave naturally’.

In my own opinion intelligent wild animals should only be removed from their natural environment if there are very good reasons.

Posted by John Blatchford

Planktonic organisms are technically ‘those which are made to drift’ by water movement. Some of the larger animal plankton might be able swim reasonably well, but even so they are very much at the mercy of the ocean currents.



Daily Vertcal Movement

Even very poor swimmers can manage to move up and down in the water column. Many phytoplankton move down during the night, and then back towards the light during daytime to allow photosynthesis. Most zooplankton (animals) move up at night to feed, and then return to deeper water during daylight hours to avoid predators (or at least to make it harder for predators to find them!).



Daily Horizontal Movement

Ocean currents typically flow in different directions as you move vertically through the water column. This means that any animal that has the ability to descend during the day will come up into a new part of the sea next evening – giving it new pastures to graze. Going up and down regularly (relatively short distances) can lead to an efficient zigzag movement through new feeding areas.



Seasonal Movements

Plants need nutrients and sufficient sunlight to photosynthesise. Away from the tropics, as day-length increases the phytoplankton ‘blooms’ and populations of zooplankton feeding on these plants explode. When the nutrients have been used up many of the phytoplanctonic organisms sink and enter a resting period – waiting for upwelling currents to replenish the surface waters and for sufficient daylight to return.

Many of the animals also move away from the surface until next season (Antarctic Krill, for example, hide away under the pack-ice.)

Posted by John Blatchford

Whalebone

The Baleen Whales do not have teeth; instead they have fringed plates made of keratin (the material that makes hair and finger nails). These ‘baleen plates’, also known as ‘whalebone’, are used to sieve small animals from the water. Right Whales and Bowheads feed by swimming along with the mouth open and straining out small animal plankton, Grey Whales scoop up sediment from the ocean floor and feed on the small crustaceans that live in the mud and sand, and Pygmy Right Whales probably feed on copepods – although very little is known about them.



Rorquals

All other Baleen Whales have pleats in the throat to allow the mouth to expand, and they are known collectively as the ‘rorquals’. They do not so much skim the water as gulp it, with the ‘pleats’ stretching to form an enormous mouth which can hold up to 100 tons of food and water in the case of the Blue Whale. Blue Whales, Fin Whales, Sei Whales and the small Minke Whales all eat plankton, but Bryde’s Whale, the Pygmy Bryde’s Whale and the Humpback prefer fish. That is all of the rorquals except for Balaenoptera omurai which was only recently discovered and has no common name as yet.



Classification

The possession of whalebone is common to all of the suborderMysticeti, but their exact relationships to each other are not clear. They all evolved from toothed ancestors and were probably all fish-eaters in the past. The change of diet (of most of them) has put them very close to the start of the ocean food-chain, allowing them to harvest the enormous numbers of small planktonic organisms which feed directly on the microscopic phytoplankton. This abundant and nutritious diet has allowed some of them to become the largest animals on earth.

Posted by John Blatchford

Here is a list of my ‘Whale’ articles so far:

Baleen Whales

Right Whales – 4 species - My article about the Bowheads and Right Whales covers the whole family (Balaenidae)

Rorquals – 8 species - Humpbacks are not, in many ways, typical of the family Balaenopteridae (the rorquals), and a better representative might well be the Blue Whale (an article is planned for very soon to present names at least, of all other rorquals).

That will only leave 2 species; the Grey Whale and the Pygmy Right Whale, each in a family of their own. These two are neither Right Whales nor Rorquals, but they are certainly among the 14 species of Baleen Whales

Toothed Whales

Oceanic Dolphins – 40 species - Risso’s Dolphin and the Killer Whale are my two dolphin articles so far (the Killer Whale is a dolphin). I wrote about Risso’s Dolphin because I find the story of ‘Pelorus Jack’ very interesting, and then about Killer Whales because … well because they’re fantastic! I also wrote an earlier article about Dolphin Conservation where I looked at some of the problems whales face. There are about forty species of dolphin (although six of them are usually called whales).

River Dolphins – 4 species.

Porpoises – 6 species - Dawn Smith has written a nice article about the Vaquita (which is close to extinction).

Family Monodontidae – 2 species – both the Beluga and the Narwhal are covered in my article ‘White Whales’.

The Sperm Whale is in a family of his own, but there are also the closely related Pygmy Sperm Whale and Dwarf Sperm Whale.

That only leaves the Beaked Whales – about 20 species – and very little is known about most of them!

See also 'Marine Mammals'.

Posted by John Blatchford

‘The Open Ocean’ suggests trying to grow plankton – here are a few further thoughts.

Choice of Zooplankton

Many copepod species could arrive accidentally with ‘live rock’, or they might be obtained from a fellow aquarist, but if you begin like this you will have no idea which species you are rearing (this might be fine for feeding the fish, but it will limit the scientific value of your observations). If you want to increase this scientific value then you will need to know which species you have. I would suggest trying a harpacticoid copepod, because they can graze phytoplankton or eat detritus, are very robust and many small fish like to eat them. You might have to splash out and buy a pure culture (maybe of Nitokra lacustris).

Choice of Phytoplankton

Again it is perfectly possible to ‘see what arrives’ in your tank, but as with the copepods (above) you will not know what you are feeding your copepods on and the scientific value will be limited. Once again you might decide to fork out for a pure culture (maybe of Thalassiosira weissflogii).

Light Intensity

N.lacustris has very small young which do not swim and will feed in the sediment at the bottom of the tank. When they grow into adults (life-cycle of 10/12 days) they will begin to swim weakly in the water and graze the T.weissflogii. The trick will be ensuring that their plant food grows at the correct rate, and experimenting with different light intensities and day-lengths could get you there!

If you try this then please report your findings by contributing to the discussion.

Posted by John Blatchford

Marine Aquaria

Ret Talbot has already written several articles about ‘Biotope Tanks’ (see Biotope-Based Marine Aquaria, Setting Up a Simple Refugium, Growing Mangroves for Aquarists, Marine Aquarium Biotoping, and The Display Refugium ), and he plans to write more. These are specific ‘how-to’ articles which suggest that hobbyists experiment with the ideas.

Ecological Studies

Each time a new refugium is set up something will be learnt. The experiment might succeed, or it might fail in some respect and lead to either a re-think or modification. This is all valuable information, and it would be good if these experiences could be shared. I have started a discussion forum to allow this sharing of ideas which follows on from the suggestion in my own article ‘Biotopes and Habitats’ that hobbyists can contribute significantly to our understanding of reef systems.

Sharing Information

There are thousands (maybe millions?) of people who keep marine aquaria around the world. If only a few of these experiment carefully with the idea of ‘biotope-based refugia’ much could be learnt. Hobbyists have great enthusiasm and persistence, (it is often said that people work harder at their hobby than their ‘day-job’!), and if only a few of those who experiment share their experiences we could get onto an exponential learning-curve.

So – if you try something new tell the rest of us how it went by adding a comment in the discussion forum.

Posted by John Blatchford

Ret Talbot and I are continuing to write about the idea of trying to set up marine aquarium systems that are as natural as possible. Reef Aquarium introduces the hobby, and the two articles that follow (‘Biotopes and Habitats’ and ‘Marine Aquarium Biotoping’) go a little further to explore the idea of Biotoping.

Specific biotopes are discussed in a bit more detail in ‘Mangroves and Seagrasses’ and ‘Growing Mangroves for Aquarists’ – with the first looking at their roles in nature and the second explaining how to build these biotopes into the tank system.

The last article (so far!) goes much further by suggesting how the hobbyist might set up a series of tanks based on a very specific natural reef system (‘Replicating Habitat in the Tank’). When this is attempted we begin to move towards the situation where amateurs can really add to our understanding of natural reef ecosystems. - by working out how individual plants and animals contribute to maintaining water quality and keeping corals and reef fish happy we can help people who are trying to save what is left of the world’s coral reefs.

As always we would encourage hobbyists who experiment with these systems to contribute to the discussion so that others can learn from successes and failures.

Posted by John Blatchford

History of Glass Aquaria

In the mid nineteenth century people began to keep fish in glass tanks, but without electricity in the home it was difficult to control the temperature. Tropical freshwater tanks were possible as soon as electricity was installed (early twentieth century in many places), and the keeping of tropical marine specimens in the home took off in the 1960’s with the development of silicone sealants. This overcame the problem of metal frames and made it possible to build large all-glass tanks for the first time.



Biotope Aquaria

In the mid nineteenth century people were keeping freshwater aquaria stocked with an assortment of cold-water fish, plants and invertebrates - attempting to create stable aquatic environments. This approach is still found in many public aquaria, and practiced by many hobbyists, and it can lead to satisfying displays which look very much like the ‘real thing’ and are relatively stable. It is unfortunately rather difficult to set up this sort of ‘biotope aquarium’ with marine systems because the different organisms that need to work together are usually best kept separate from one-another.



Biotope Tanks

Recently people have begun to experiment with systems which involve a number of small tanks that are linked to the main display aquarium. These ‘biotope tanks’ house the more delicate (or unsightly!) organisms that are needed to help purify the water and cycle nutrients efficiently. Ret Talbot has a number of articles which go into the practical side of this technique, and I have written about some of the theoretical aspects (see ‘how to set up a display tank’ and ‘Biotopes and Habitats’ for examples).



Discussion

Both Ret and I would like people to let others know about their successes and failures through the discussion forum.