We know the history of the whale hall, the date the whales were collected and which species each whale is but what we don’t know is how old the whales are. Are they baby whales or grandma whales? How can we tell?
The answer is in the morphology of the bones. The vertebrate skeleton (such as a whale’s) begins as cartilage which is then ossified (replaced by bone) as the animal grows. However at the top and bottom of the bones a strip of cartilage remains, this is known as the growth plate.
This cartilaginous plate provides a growth zone in an otherwise fully ossified bone allowing bones to increase in length and size during development. The cartilage grows continually and is steadily replaced by bone until a final size has been achieved, then the remaining cartilage will stop duplicating and is ossified, permanently closing the growth plate.
By examining the whale skeletons and looking for growth plates – which will look like gaps in specific parts of the bones as the cartilage is not longer in situ – we can tell if the individual was still growing or was a fully grown adult.
The answer is in the morphology of the bones. The vertebrate skeleton (such as a whale’s) begins as cartilage which is then ossified (replaced by bone) as the animal grows. However at the top and bottom of the bones a strip of cartilage remains, this is known as the growth plate.
This cartilaginous plate provides a growth zone in an otherwise fully ossified bone allowing bones to increase in length and size during development. The cartilage grows continually and is steadily replaced by bone until a final size has been achieved, then the remaining cartilage will stop duplicating and is ossified, permanently closing the growth plate.
By examining the whale skeletons and looking for growth plates – which will look like gaps in specific parts of the bones as the cartilage is not longer in situ – we can tell if the individual was still growing or was a fully grown adult.
After close examinations of all 8 whales in the hall we found that every one of the whales had open growth plates in one or more bone – we found them in the vertebrae, scapular, ulna, radius, and humerus. This indicates that all of the whales were still growing and although we cannot give them a specific age we know they were not fully, skeletally mature.
Unfused growth plates in caudal vertebrae. Indicated by white arrows. Sei whale.
A close up of the unfused vertebral gowth plates. Sei whale.
Growth plates at the humerus, ulna and radius. The ulnar plate is partially fused. Sei whale.
A close up of the growth plates at the elbow.
Catherine, the anatomist on the team is currently researching how we can use the growth plates that have been found to provide a more specific age for each whale. The use of ossification status has been extensively researched and utilised to estimate chronological age in many mammalian species but due to the obvious limitations in studying the skeletons of these huge, rare, aquatic animals more research, such as that being carried out here in Bergen whale hall is required to answer our questions about whale age.
I need to contact you regarding scientific project on whale bones please provide me your email
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Marcin