Thanks for tuning in for another episode of Inside Nature’s Giants: The Sperm Whale. In this episode, biologists and veterinarians use any means necessary (including chainsaws and cranes!) to investigate the anatomy of a recently stranded sperm whale and determine why the animal died. Although I have only participated in one whale beach necropsy, I liked this episode because I think that it gives a good representation of what dissecting large stranded marine animals entails. Dissections are usually delicate and precise, and I think this is what makes large marine mammal dissections so unique. You need to have finesse while utilizing tools like chainsaws and gaffs. This episode was a bit gorier than the leatherback sea turtle episode but just as interesting! Let’s get into the highlights! (As always, I give timestamps for the more adventurous viewers.)
3:40 – The host introduces the whale that stranded on the southeast shores of England and explains that there are two types of whales: Baleen and Toothed whales. Richard Dawkins also elaborates on the differences between the species at 6:16, and he explains that whales are large mammals that had land ancestors. The land ancestors returned to the sea and subsequently split into the two groups of whales that we see today. The episode did not go into many specific details about the differences between whales, so check out this link from NOAA for more helpful information.
12:04 – This excerpt compares physiological differences between humans and sperm whales in regards to deep diving. Sperm whales can hold their breath for up to 1.5 hrs when they are hunting, but humans can only stay underwater for around 3-4 minutes with specialized training. Both humans and whales strive to conserve their energy when diving. Humans can reduce their heart rate to about 35 beats/min, but sperm whales are thought to lower their heart rate all the way down to 1 to 2 beats/min!
15:12 – Even though they look nothing like humans on the outside, sperm whales are still mammals, and, consequently, they also develop a belly button from their umbilical cord. The video shows a cool clip of a baby sperm whale with a partial cord still attached. Evidently, baby sperm whales can suckle for up to about 13 years! Sperm whales have close social ties and when a mother has to hunt, relatives will look after the baby for her.
17:44 – Sperm whales primarily eat squid. Squid beaks are not easily broken down in a whale’s digestive tract. Therefore, biologists usually find a multitude of squid beaks within the stomachs of sperm whales. Sometimes, when a sperm whale tries to pass the beaks, the beaks get covered in a waxy substance called ambergris. Ambergris was popularly used in perfumes or even eaten! The largest chunk of ambergris was sold for approximately 7 million euros! If you are a Bob’s Burger fan like me, you might enjoy their explanation of ambergris. 🙂
22:43 – Sperm whales have incredibly dark musculature due to the high quantity of myoglobin in them. Myoglobin helps store oxygen for the whale’s deep dives.
24:13 – Sperm whales have three stomachs. This particular whale had lots of parasites and also no food in its stomachs. As sperm whales cannot hydrate by drinking salt water, they obtain water through their diet. Without food, they die from dehydration, which is what the biologists think happened in this case.
27:28 – I really liked this bit of functional anatomy. Sperm whales have jointed ribs that aid in their diving dynamics. When sperm whales dive, the pressure increases, which changes the volume of their lungs. To accommodate the change in pressure, the ribs fold in (kind of like an elbow joint)! The episode shows a neat animation of this at 28:35.
33:32 – Dissecting the mouth of the whale. Sperm whales really only have teeth on the bottom jaw, and the upper jaw is comprised mainly of corresponding holes in the gums. However, in this episode, they did find a vestigial tooth in the upper jaw!
41:22 – A quick look at another type of toothed whale, the common dolphin. The episode also explains about echolocation in the sperm whale. Researchers have discovered that different whales have unique clicks and dialects!
54:40 – A brief look at the inner workings of the sperm whale heart.
56:00 – Sperm whales have two lungs, but, interestingly, their lungs do no possess lobes or sections. This physiology helps the whale with its explosive breathing/recovery after dives but makes it trickier for them to fight off respiratory infections.
57:30 – Spermaceti! This was the culmination of the entire episode. The liquid, spermlike/waxlike oil substance takes up a large portion of the whale’s head and is what gave the whale its name. A full grown sperm whale can possess approximately 3-4 tons of spermaceti. This precious liquid was used in lamps because of its smokeless properties and also in machines to help lubricate parts. The useful properties of spermaceti made the sperm whale a popular target in the whaling industry. However, it is probably most useful when left inside the whale (1:02.00). Spermaceti is vital for whales to produce their echolocation clicks. The clicks help the animals navigate their environment, hunt, and even attract mates. Because of the internal dynamics required to produce clicks, female sperm whales are able to tell that larger (aka more desirable) whales have a longer interval between their clicks! Moreover, because spermaceti begins to solidify under colder temperatures, sperm whales can regulate the density of their spermaceti for diving by warming it with their body temperature or “snorting in” cold sea water.
1:03.39 – The organ responsible for the sperm whale’s characteristic clicks is an organ known as “the monkey’s muzzle” (phonic lips in above diagram). This organ is made up of two lips that vibrate when air passes through them. The vibrations are amplified back to the skull of the animal through the spermaceti and then back out through the head via the melon. The video gives a good animation of the whole process (1:07.17).
1:08.10 – The episode ends by briefly discussing the reproductive system of sperm whales. The males have a prehensile penis, and sperm whales are one of the few mammals that mates belly-to-belly.
I hope you enjoyed the second installment in Bloggerheadseaturtle’s The “Inside” Scoop and learning about the impressive anatomy of the largest member of the toothed whales!