To Breed some Animal Species in Captivity

Why is that so Hard or Impossible?

I suppose I have mentioned a few times before that I love fish (and not only to eat) and that one of my hobbies as a teenager was to keep and breed aquarium fish. At that time the big challenge was the Amazon Blue Discus Symphysodon aequifasciatus, because food, temperature, aquarium plants, lighting, the pH and the hardness of the water  – they all played critical roles. When captive breeding eventually succeeded, the price of this formidable species came down significantly. Another blue species (and there seems to be something with the colour of “blue”) is the marine Blue Tang, which has also been difficult to breed (like other coral reef species), but recently has become possible. But why do people want to breed fishes in captivity anyway? One of the main reasons would be the commercial aspect (some species are valuable as a food item and some in the aquarium trade as pets). But there is also the aspect of safeguarding that a species in the wild does not become overfished and ultimately extinct. A third reason would be vanity, namely to be the first person to succeed in finding a way to successfully breed a species that others had found impossible to breed.

But what actually makes it so difficult to breed a species, whether it’s a fish, a bird, a mammal or indeed any animal, in captivity? Looking at the two marine organisms that I had been associated with first, namely eels and rock lobsters (also known as spiny lobsters or ‘langouste’), it is mainly the fact that the larvae of these species spend a long time as marine plankton in the ocean and need a special kind of food that is difficult to prepare and to administer in captivity. Although one Japanese lab has succeeded to rear the Japanese eel Anguilla japonica from egg to a young individual, the effort in terms of costs and equipment is prohibitive and not yet a solution to reduce the collecting of eel fry and glass eels when they arrive from the ocean to enter freshwater and to curtail their sale to eel farmers who then fatten them up to turn them into young and sellable eels. A similar story is that of rock/spiny lobsters: for 20 years Japanese researchers tried to copy the entire life cycle from egg to marketable size in the lab of Panulirus japonicus and the best they could achieve was that about 1 out of a thousand larvae that hatched from the eggs in the lab and were then looked after for many years, would in the end survive to maturity. Commercially that would have been a flop and the research was terminated (at least in the lab to which I had sent a student to work in).

Not only are some aquatic species, and in case of the marine ones, hard or impossible to breed because of their long larval and planktonic phase (and also their size when thinking of tuna fish, the Blue Marlin or giant squid), but there are also the specific water quality requirements especially in case of the freshwater forms. However, some birds, mammals and other animals are equally well known to be difficult to breed in captivity and the cheetah and the panda are good examples. For the panda the extremely short oestrus period of 1-3 days/year is one problem, its choosiness regarding partner compatibility and its specific food requirements are another. Food for captive cheetahs is not a problem, but the very low sperm count in males is; the genetic relatedness of all extant cheetah individuals and the high mortality of the cubs are further notorious difficulties.

When it comes to birds (and apart from chickens and pigeons I never kept any), I heard that some parrots are not easy to breed and that especially their chicks require a great deal of care. I also don’t believe that it can be easy (or can be done at all) to breed swifts, house martins and swallows in captivity.  Or, thinking of cuckoos that need a host species’ nest with eggs in it, so that they can add their own egg to those of the hosts. Adult albatrosses cannot even be kept in a cage, let alone ‘be persuaded’ to construct a nest and breed in it. In fact keeping and breeding sea birds in captivity would be a challenge best left alone and forgone in favour of protecting these birds’ wild breeding places. There are, of course, many, more species of animals that are inclined not to breed in captivity, but I realize that for some, sadly, captive breeding may be the only way they will survive as a species so that our children and their children can see them ‘for real’ and not just in the computer or books.

© Dr V.B. Meyer-Rochow and, 2021. Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and with appropriate and specific direction to the original content.

Studies that haven’t been done, but can and should be done

One of my weekly science blogs in the past had dealt with “Experiments that shouldn’t be done, can’t be done or can but won’t be done”, but I also think of studies that haven’t been done, can be done and should be done. Some (that I won’t disclose in this blog), I may be able to tackle myself in the future, others that I shall now mention are projects I’d love to carry out but for various reasons won’t be able to.

Honey bees, for example, are known to rather precisely visit flowers when they open in the morning and reveal their pollen and nectar sources. One can even teach bees to arrive at a feeding table at a particular time, e.g. 09.00 o’clock, to lap up a sugar solution reward. During spring in northern Finland the days get longer every day. Depending on the latitude the differences from day to day can be as big as 15 to 20 minutes during the maximal daytime lengthening period in March and April. Bees, we all know, are smart little insects, but can they anticipate time shifts? Once trained to receive food at 9.00 o’clock on day one, but then given food at 9.20 the next day, 9.40 the following, 10.00 the day after that, etc, i.e. with a 20 minute delay each successive day, would bees understand that food appears a little later every day? It would be remarkable if they could adjust to the constantly delayed feeding time and anticipate the correct time of feeding, appearing at the feeding station 20 minutes late each day.

My second project involves aquatic newts; vertebrates in other words that are famous for being able to regenerate severed body parts, including legs, parts of the tail, even an eye. But does “exercise” speed up the regeneration and healing process? If one surgically removes the last 1 cm of the tail of a number of identically long newts and keeps half of the operated animals in an aquarium with water filled to a depth of 2 cm, they would not have to swim to the surface to take a breath of air, but simply lift their head out of the water. The other half of the operated animals should also be kept in an aquarium, but filled with 25 cm deep water. If they want to take a breath of air, they’d need to swim to the surface and thereby use their now shortened tails for propulsion. My working hypothesis is that the newts which are forced to exercise their tails will experience a faster tail tip regeneration. And that could be interesting.

My third project is more involved and cannot be done by a single scientist. The idea for this project came to me a long time ago when I participated in the “Walther Herwig” fishery research expedition to the South Atlantic Ocean in 1967. When the ship crossed the so-called Walvis Ridge off the coast of Namibia, I studied the hydrographic charts, because I was interested in trying to catch some deep sea organisms with a special deep water net. The chart revealed that the submersed Walvis Ridge was a 3000 km long mountain range in an East-Southwest direction with multiple, deep canyon-like valleys, separated from neighboring ones by mountain ranges often 2 – 3,000 metres high as well as many seamounts mapped in 2012 by Oregon State University’s 2012 “R/V Melville” cruise MV1203. Obviously there was in the Walvis Ridge the possibility of rather isolated ‘pockets’ of very deep environments protected and shielded from neigbouring deep sea “valleys” by seemingly high barriers, sea mounts and guyots.

Not having followed up marine research in that part of the Atlantic, I cannot say for certain whether these “underwater valleys” have received any attention and whether, in fact, the hydrographic charts I had seen were reliable and correct. However, assuming they were representing the real situation, then I’d expect some unique benthic organisms in these deep underwater canyons and valleys. Pelagic fish can probably swim across the mountainous barriers, but organisms at the bottom? For them it would be harder. If I had the means, I’d organize an expedition to this part of the world to explore the “Deep Unknown in the Valleys of the Walvis Ridge” and recover treasures of hitherto unseen organisms!

© Dr V.B. Meyer-Rochow and, 2021.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and with appropriate and specific direction to the original content.

biology zoology blog benno meyer rochow honours animal

The Animals that Played a Role

How to honour and remember them

I remember when I worked at Yokohama City University once a year in autumn all of us who carried out experiments with or on animals had to go to the temple and pray for the souls of these animals. Our boss used to joke and say we don’t have to pray too hard because our work involved crabs and insects, but those in sports medicine using dogs, they have to pray much harder. It’s actually a tradition that came to Japan from India via China to think of animals or free some during the festival of Hojyoe. There are, of course, other ways to show one’s appreciation of an animal that has played a major role in someone’s life and “Cher Ami”, a pigeon, was awarded “le Croix de Guerre” by the French Government for having been a successful war spy. Recently a cat named Choupette inherited millions after its owner, the fashion designer Karl Lagerfeld, had passed away. Another fashion designer (Alexander McQueen) left 50,000 British pounds to his pet dogs when he died in 2010 and the American TV personality Oprah Winfree is said to have plans to leave millions to her dogs. I wouldn’t be surprised if Brigitte Bardot has similar plans. —>—>