Week 4
24 July 2006

Blue Whales
(Balaenoptera musculus)

The Blue Whale is found in many oceans of the world, but there are isolated populations in the North Pacific and North Atlantic as well as the Southern Ocean. This group in the Southern Ocean may spend summers as far south as the Antarctic pack ice, at a latitude of  40 degrees South. They have been recorded as far south as 78 degrees latitude. In the winter, they have been observed as far north as Ecuador and Rio Grande de Sul, Brazil.

Question: Which country borders the Atlantic and which country borders the Pacific?

Population: The total Blue Whale population is estimated at about 9000 with 710-1255 in Antarctic waters.

The Blue whale was camera shy, but other whales posed for the journal.

Physical Characteristics: The Blue Whale is the largest whale and among the largest animals on the planet. Its color ranges from pale gray-blue to dark slate gray.  The baleen plates appear jet black although they gray with age.  Blue whales range in length from 20-33.6 meters. They usually weigh between 80-150 metric tons. They are able to swim at speeds of more than 30 km/h.

Question: If a whale were swimming through a school zone (After all, there are schools of fish in the ocean.) would the whale get a ticket for excessive speed?

Identification: The blow from these whales can be 9-12 meters high; they are dense and upright. The blows occur every 10-20 seconds over a 2-6 minute period before diving.

The Blue whale was camera shy, but other whales posed for the journal.

Question: You are standing at the coast watching the blue whales. You have noticed that one particular whale blows every 12 seconds for a 5 minute period before diving. You are now going to amaze your friends by telling them when the whale is going to dive. How can you figure this out?

Diving: Blue Whale dives can last 50 minutes but they are usually 5-20 minutes. They can reach depths of 150-200 meters.

Social Behavior: Whales travel in groups of 2-3, but larger groups of up to 50 whales may be found in feeding areas. The whales rarely breach in the Southern Ocean, but raise their tail flukes more often than those at higher latitudes.

An Orca whale smiles for the camera

Diet: Blue whales eat only larger zooplankton, those that are at least a few centimeters long. Blue whales can consume 3-8 metric tons of zooplankton daily.  They feed within 100 cm of the surface in the evening and up to 100 meters below the surface during the day.

Question: Are blue whales carnivores or herbivores? How do you know?

Conservation Efforts: The most hunting of Blue Whales occurred during the first third of the 20^th century. Thirty thousand were killed between 1930-1931. Most of this hunting took place close to the polar ice where the whales feed on krill during the summer. Commercial hunting of Blue Whales is now prohibited. 

The Blue whale was camera shy, but other whales posed for the journal.