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Research has always been a very important part of DRC's focus. After all, research is our middle name! DRC evolved out of the Institute for Delphinid Research. When DRC's founders took over the facility in 1984, research remained a high priority. We have since expanded our in-house research goals, and also worked with world-renowned scientists who have come to DRC to study our resident colony of dolphins. General areas of interest include marine
mammal cognition, communication, calf
development, and husbandry.
DRC is excited to announce that the findings of our study Understanding of the Concept of Numerically "Less" by Bottlenose Dolphins (Tursiops truncatus) have been published by the Journal of Comparative Psychology (Vol. 119, No.3, pages 296-303)! The study, starring Talon and Rainbow, demonstrates conclusively that dolphins grasp the concept of relative numerousness.
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Read about the study in the American Psychology Association's Monitor on Psychology (Vol. 36, No. 8)
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See the story which aired on the Discovery Channel!
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Can Dolphins do Math?
One of the more popular questions we are asked is "How intelligent are dolphins?" One way to try to answer that question is to measure dolphins' abilities on various mental tasks. Our staff, led by Dr. Kelly Jaakkola, is investigating whether dolphins have specific math abilities. These abilities can be grouped into four basic number concepts:
Numerosity
Are these hands holding the same thing? Well, yes and no. They both have rocks, but they have different numbers of rocks. In other words, what's different is the characteristic we would call quantity. Scientists call this concept numerosity. |
2 rocks in one hand,
4 in the other |
Relative
Numerosity
("More" and "Less")
A slightly more difficult concept is that not only are "two" and "four" different from each other, but that numbers have a specific order. That is, "two" is less than "four", "two" is more than "one", and "four" is less than "six". |
Quantities
can be arranged
in an order, from less to more. |
Mapping symbols to
Numerosities
A more abstract number concept involves the ability to recognize that a symbol (like a written numeral) can stand for specific quantities of objects. |
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Manipulating
Numerical Symbols
(Addition and Subtraction)
The ability to manipulate numeric symbols, as in addition and subtraction, is an advanced skill that is generally taught to human children in school. Chimpanzees are the only other species besides humans that are known to have this ability. |
Symbols can be manipulated
just
like the objects themselves |
Understanding
of the Concept of Numerically Less |
In
our “Less” project, we researched the
ability of dolphins to understand the first two
concepts -- numerosity and relative numerosity.
Two of our star research pupils, Talon and Rainbow,
participated in this study. We began by showing
each dolphin two boards with different numbers
of dots on them: 2 and 6 for example. First, we
asked them to always pick the board with 2 dots
on it, no matter where the dots were on the board
or what size they were. |
Talon choosing
the board
with “less” dots. |
Learning this task meant that
Talon and Rainbow understood that 2 is different than
6, which is the concept of numerosity. The next step was
to test with other number pairs that were new to the dolphins,
and always ask Talon and Rainbow to choose the board that
had the fewest dots on it. The ability to pick out the
smaller number without being trained on that specific number
meant that they understood the concept of “less”(i.e. relative
numerosity).
Reference:
Jaakkola, K., Fellner,
W., Erb, L., Rodriguez, A. M., & Guarino, E. (2005). Understanding
of the concept of numerically “less” by
bottlenose dolphins (Tursiops truncatus). Journal
of Comparative Psychology, 119, 296-303.
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Rainbow studies
the Journal of Comparative Psychology. The “Less” study
in which he participated
is in this issue. |
Abstract
In 2 experiments, bottlenose
dolphins (Tursiops truncatus) judged the
ordinal relationship between novel numerosities.
The dolphins were first trained to choose the exemplar
with the fewer number of items when presented with
just a few specific comparisons (e.g., 2 vs. 6,
1 vs. 3, and 3 vs. 7). Generalization of this rule
was then tested by presenting the dolphins with
all possible pairwise comparisons between 1 and
8. The dolphins chose the exemplar with the fewer
number of items at levels far above chance, showing
that they could recognize and represent numerosities
on an ordinal scale. Their pattern of errors was
consistent with the idea of an underlying analog
magnitude representation.
For the full text of the
article, please email: drc-res@dolphins.org. |
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CALF SOCIAL DEVELOPMENT : |
Each dolphin calf that is born at DRC is unique. We've had the
opportunity over the years to observe mother-calf relationships and record how
the relationships change as the calves grow up.
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Specifically, we record how much
time calves spend with their mothers, how much time they spend with
"babysitters" (which scientists call "alloparents"), and how much time they
spend on their own. In this way, we can answer questions such as:
- Do different mothers have a consistent "mothering style"?
- Do male and female calves achieve independence at different
rates?
- Are there differences between first-born and later-born calves
of the same mother?
- What effect does "babysitting" experience have on future success
as a mother?
Because it is so difficult to closely observe dolphin babies in
the wild, information learned through watching our calves grow up is especially
valuable.
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DOLPHIN TRACKING SYSTEM FOR HURRICANES : |
How can we help our dolphins find their way home after a major hurricane?
Located on Grassy Key, Florida, DRC faces the possibility of hurricanes striking the area each year. Depending on the severity of a storm, some dolphins may feel more secure seeking shelter in deeper water away from shore. Once the storm has passed, it is critical that we are able to quickly find any dolphins that do not return on their own, as animals that live in human care lack the necessary skills to survive in the wild.
Over the years, DRC staff has worked on several different approaches to assist in recovery. Every dolphin at DRC has been trained to respond to a recall device (a "pinger"). This behavior is practiced and reinforced regularly. In order for this to be effective, however, the dolphin must be within a 1-2 mile range of the recall device. To place human rescuers within this range, DRC has sought to mark the members of its colony in a readily recognizable way. It is believed that if a dolphin were lost, (s)he would seek out humans for assistance, increasing the likelihood of the public spotting the dolphin. Once the sighting was reported, DRC staff would be able to use the recall device in that area
We have developed bands that are custom fit to each dolphin’s peduncle (the portion of the tail just before the flukes). Made of a durable, but pliant material, the bands are brightly colored so that when a banded dolphin is spotted, (s)he will be immediately identifiable as a dolphin that belongs at DRC. |
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We are also investigating the possibility of a noninvasive radio transmitter. Ideally, the transmitter would act as a locator, providing us with information on the whereabouts of a dolphin at a given time. This would be a more reliable and effective methodology of recovery, allowing us to expand our search area by many miles, without relying on a public sighting. Radio transmitters are a proven technology; our task is to develop a temporary attachment method. DRC is committed to accomplishing this task in a noninvasive manner.
Find out how you can help with this life-saving effort here.
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What more can we learn about the care of DRC’s pod?
Although there have been great advances over the past few decades in the field of dolphin husbandry, there is still much to be learned. Staff at DRC collect data under a variety of circumstances to monitor the general health and well being of our family of dolphins and sea lions.
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For example, if a dolphin moves into a new lagoon, we want to ensure that (s)he is comfortable in that new environment and social grouping. Or, if a dolphin is feeling a little under the weather, we may monitor their respiration rate. Information like this can help us to make decisions to promote the health and happiness of the dolphins and sea lions that call DRC home.
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BIOLOCOMOTION (TAIL WALKING) : |
Dolphin Research Center is participating in a study by Prof. John Bush and Dr. Matthew Hancock of the Massachusetts Institute of Technology, and Prof. Frank Fish of West Chester University. These scientists are looking at the ability of dolphins (and some fish) to walk on their tails with the bulk of their body above the water. This ability is referred to as tail-walking, and is a common trained behavior for the dolphins at DRC.
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Rainbow demonstrates his beautiful and
powerful tail-walk! |
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DRC has a long history of successful dolphin births. Since we have always structured our dolphin living arrangements based on personalities and what we know of natural dolphin society, there often has been more than one mature male present when a female conceives. Prior to new developments in paternity testing, we had no reliable method of identifying a calf's father.
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Rainbow and Pax, shown by DNA
tests to be father and son. |
DNA Fingerprinting
In the 1980s, DRC began a genetic study to develop a method to determine paternity in conjunction with Dr. Debbie Duffield at Portland State University. Dr. Duffield extracted chromosomes from blood samples taken from our dolphin colony and compared them to determine paternity. By the early 1990s the technology available to Dr. Duffield had improved considerably thanks to advances in human paternity testing. The improved technique, called DNA fingerprinting, produced results much faster than the older chromosome analysis. Dr. Duffield first tested dolphins whose paternity had been formerly determined with chromosome analysis. The results were identical, proving that the new technique was valid for dolphins. Thanks also to DRC’s careful record keeping, Dr. Duffield was able to further demonstrate the accuracy of DNA Fingerprinting with newer calves because she knew exactly which male dolphins were candidates for father of a particular calf.
As a result of this testing, DRC knows the fathers of the dolphin calves born at DRC. Delphi has sired most of our babies to this point, having fathered four calves, including Merina, Santini, Aleta, and Talon.
DNA Microsatellite
As technology advanced, Dr. Duffield discovered an even better way to conduct dolphin paternity tests. The newest technique, using microsatellites or specific pieces of DNA, is a great improvement over DNA fingerprinting for analyzing the genetics of wild populations. With DNA fingerprinting, Dr. Duffield had to test every possible father along with the calf and its mother at the same time, very inconvenient when numerous males are candidates for the father in a wild population. Results could not be compared between tests, so with each new calf, all of the fathers had to be tested again.
Microsatellites, on the other hand, are easily extracted from a dolphin blood sample for analysis. Once analyzed, the specific pattern for each dolphin can be documented for future comparison.
To test the microsatellite technique, Dr. Duffield ran samples from Rainbow, Sandy, Tursi, and Pax. Because DRC knew that only Rainbow or Sandy spent time with Tursi, Dr. Duffield was able to show that the new technique accurately predicted Rainbow as Pax’s father. Dr. Duffield is now using this technique with the wild dolphin population under study in Sarasota, FL.
DNA tests can help DRC quickly and accurately determine the paternity of our calves in the future. This knowledge of the family history of our calves is critical to future planning for our breeding colony.
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