Rice’s Whales: one of the newest species of baleen whales

This month, we will celebrate the newly classified species, the Rice’s whale (Balaenoptera ricei)! Once mistaken as the Bryde’s (pronounced “broodus”) whale, new evidence proves the rice whale is different, both morphologically and genetically!

Bryde’s whale – Wikipedia

Same but Different

Because of their similar features, scientists misclassified the Rice whale for the Bryde’s whale. They have similar features. Males are typically smaller than their female counterparts. They both have a similar shape to the sei whale, however, there are minute differences. Rice’s whales prefer warmer waters. The Gulf of Mexico can reach temperatures of about 74-82F (23.3-27.8C). This is crazy warm compared to their counterparts! Another attribute that sets them apart is their 250-410 short baleen dark grey to black baleen plates with white bristles on each side of their mouth.

Unlike the Bryde’s whale that feeds near the surface, the Rice’s whale feeds just at or above the seafloor. Scientists continue to research their diets. What do you think they could be snacking on?

Ingredients for a new Species

Dr. Patricia Rosel and Dr. Lynsey Wicox began collecting tissue samples of the Rice’s whale back in 2000. Over the years, they collected 36 different individuals. They noticed a few differences here and there with their genetic makeup; however, their skulls set it apart.

The Rice's whale
The left is a Rice’s whale skull, while the right is the Bryde’s whale skull. Both images are from Rosel et al. 2020

As seen in the picture above, there is a broad gap between the nasal bones that does not narrow (the left is Rice’ whale, and the right photo is Bryde’s whale). This is created by the frontal bones, which protrude anteriorly between the posterior end of the nasals. During a stranding event in 2019, it washed ashore on the Florida coast, where two of our past featured Whale scientists, Meghan Sutton and Madison Hahn, aided in the necropsy! The Rice’s whale skull found its way to Dr. Rosel after the necropsy, giving her the opportunity and discovery of a lifetime! She compared it to several baleen skulls and concluded that this, along with genetic samples, was, in fact, a new species!

Threats to the Species

The Gulf of Mexico is vital to humanity and thus highly utilized by anthropogenic activities. The northern Gulf of Mexico experiences high shipping traffic that overlaps with Rice’s whale habitat. In 2009, a female Rice’s whale washed up dead in Tampa Bay. After completing the necropsy, scientists deduced that her cause of death was vessel strikes. On top of vessel strikes, Rice’s whales need to worry about noise pollution. Various human activities in the Gulf of Mexico produce a significant amount of underwater noise, such as shipping traffic, rig use, seismic airgun surveys, etc. These low-frequency noises overlap with the hearing range of Rice’s whales. It is likely they rely on their hearing to perform critical life functions such as communication, navigation, finding a mate, locating prey, and predator avoidance. The resulting disruption can seriously alter their life functions.

Risk of Oil Spills

Due to expansive energy production and exploration, the Gulf of Mexico is highly industrialized. North-central and western Gulf of Mexico contain thousands of oil and gas platforms, overlapping with the Rice’s whales’ historic home range. Oil spills are a common occurrence in the Gulf of Mexico too. Exposure to oil spills may cause severe illness or death of marine mammals. Chemicals utilized to clean up the spills could also be toxic to the Rice’s whale. These events can kill their prey, too, causing further indirect consequences.

In 2010 the Deepwater Horizon oil spill created negative impacts on its immediate spill range and the entire Gulf. While the DWH platform was located outside the Rice’s whale range, scientists estimate half of the oil spill footprint overlapped with the whales’ habitat. Scientists estimated that their population decreased by 22%.

Unfortunately, there are now an estimated to be less than 100 individuals left, classifying them as endangered…

Thanks for Reading!

Here are a few links you can click if you want to learn more!

Did you like this post on Rice’s whale? Come read out other posts on baleen whales:

The Sei Whale – November 2020

Naomi Mathew is a PhD student at University of Louisiana at Lafayette. She works on bioacoustics in marine mammals from the Gulf of Mexico. She is the co-founder of Whale Scientists. You can read more about her here

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