Species Spotlight: The Blue Whale- Balaenoptera musculus

Introduction

Blue whales are known to be the largest animals ever known to have lived on Earth, their tongues alone weighing as much as an elephant (National Geographic). They can live up to one hundred and ten years old, be up to one hundred and five feet in size, and can weigh up to two hundred tons. Blue whales are carnivores and tend to travel in pods, although sometimes they do travel alone.

Taxonomy

Domain: Eukarya

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetacea

Family: Balaenoptera

Species: Musculus

Balaenoptera musculus size comparison to a human

Niche and Habitat

Blue whales are found in every ocean across the globe except the Arctic, through different types of blue whales are usually stay in a distinct area, mostly differing in temperature. B. Musculus brevicauda are typically found near the west coast of Australia to the Southern Indian Ocean. B. musculus musculus are mostly found near Iceland's and Norway's coasts and the east coast of Canada. Because blue whales' marine environment varies greatly, they share their environment with many different species of marine animals, but typically only consume krill by filter-feeding large amounts of water. Blue whales are typically found alone or in pairs, they are rarely found in small groups. Blue whales usually swim around 5 miles per hour while feeding and traveling, but can reach speeds up to 20 miles per hour for short amounts of time. Blue whales typically live around 80 to 90 years.

Evolutionary History

About 50 million years ago, the first whale appeared to be Pakicetus, a quadruped land animal with fur and external ears. About 3 million years later, Pakicetus has evolved to endure the aquatic environment for a short period to seek food or escape predators. Slowly, cetaceans adjusted to the sea and migrated from the west to the north. It's believed that whales were between 5 and 9 meters long 34 million years ago. Until about 4.5 million years ago, whales had increased their body size due to climate change and lack of resources. The increase in their body size allowed whales to travel further and take advantage of being tertiary consumers. Recent studies have found that whales and hippopotamus are sister groups through examination of their milk protein genes. As members of the Order Cetacea, their bodies have evolved to excel in the aquatic environment. Over the years, Blue whales' have restructured their forelimbs to improve steering within the water, broadened their tail to strengthen their swimming skills, and repositioned their blowhole to the head for easier access to air. Simple external features were not enough for them to endure their environment. Blue whales have advanced sensory skills since sound and light reflect differently in the sea. In particular, they have refined hearing skills as they have lost their external ears. They use air sinuses and bones to discover sounds near them. Today, whales are still evolving to adjust to climate change and ocean pollution.

Conservation

The Balaenoptera musculus is an endangered species protected under the Endangered Species Act (ESA) and the Marine Mammal Protection Act (MMPA). Internationally protected from commercial whaling since 1996, blue whales experience numerous other threats including vessel strikes, fishing gear entanglement, ocean noise, habitat degradation, pollution, and climate change. Additionally to being protected under the MMPA and ESA, continuous efforts are being made by National Oceanic and Atmospheric Administration (NOAA) fisheries, “Our work strives to protect blue whales by reducing vessel strikes, responding to the dead, injured, or entangled blue whales, and reducing the effects from ocean noise.” (NOAA Fisheries, 2022). Conservation efforts also include establishing the Blue Whale Recovery Plan, which will work to downgrade its status from endangered to threatened. The plan consists of six main goals…

1. Maintain international regulation for whaling of Blue Whales

2. Determine taxonomy, population structure, distribution, and range

3. Estimate population size and monitor abundant trends

4. Monitor the habitats important to Blue Whale populations

5. Further research on human-caused threats and potential solutions

6. Maximize efforts in acquiring scientific information from deceased specimens

Citations and Acknowledgments

Written by Casey Pardue, Anna Pederson, Jamie Lin and Sara Kiehle

DolphinDroneDom. (2021, June 7). Spectacular Images of Blue Whales (Mother and Calf) in San Diego [Video]. Youtube. https://www.youtube.com/watch?v=uRYd4QouDbQ

National Geographic. (2017, April 25). See Blue Whales Lunge For Dinner in Beautiful Drone Footage | National Geographic [Video]. Youtube. https://www.youtube.com/watch?v=cbxSBDopVyw

NOAA Fisheries. “Species Directory: Blue Whale.” NOAA Fisheries , USA.gov, 10 Feb. 2022, www.fisheries.noaa.gov/species/blue-whale.

Whales online . (2021, September 2). The origin of whales (evolution). Baleines en direct. Retrieved April 2, 2022, from https://baleinesendirect.org/en/discover/life-of-whales/morphology/les-ancetres-des-baleines/