Skip to main content

The minke whale (Balaenoptera acutorostrata)

The minke whale (Balaenoptera acutorostrata)
The minke whale (Balaenoptera acutorostrata) is the second smallest of the baleen whales, measuring about 32.8 feet (10 m) in length. A distinctive triangular head, narrow and pointed snout, and sickle-shaped dorsal fin make this whale easy to identify. Generally, minke whales are black, gray, or brown on their dorsal surface and a light color on their ventral surface. These active, agile whales have good maneuverability and speed, able to travel at 10.4 miles per hour (17 kph) for short periods of time.

As baleen whales, minkes are carnivores whose mouths are equipped with smooth baleen plates for filtering small organisms from gulps of water. Minkes can be found worldwide and are known to live in deep oceans, along coasts, and in coral reefs. Instead of seasonal migration, they only travel to follow their food. Sometimes minkes chase schools of small fish such as sardines and herring, swimming beneath and scooping them up in their open mouths. As in humpbacks, the throats of minkes are pleated so that they can expand their bite size.

Females enter their reproductive periods on 14-month cycles. Gestation lasts for 10 months, and calves are born in mid-winter. There is usually only one calf, but twins and triplets do occur. A newborn calf is only about 8.53 feet (2.6 m) long but grows quickly on its mother’s milk, which supports the baby whale for four or five months. Young whales reach sexual maturity at seven years of age and live to be about 50 years old.

Minke whales are most often solitary animals, although they are also seen in small groups. When food is plentiful, several hundred animals may congregate in the feeding grounds where they communicate with grunts, clicks, and breaching. The sounds they produce are very low-frequency waves that can travel long distances under water. Worldwide populations of minke whales are larger than most other groups of whales, consisting of about a million animals. Because the whales are small, they have escaped predation by humans and maintained almost-normal population sizes.

Popular posts from this blog

Advantages and Disadvantages of an Exoskeleton

More than 80 percent of the animal species are equipped with a hard, outer covering called an exoskeleton. The functions of exoskeletons are similar to those of other types of skeletal systems. Like the internal skeletons (endoskeletons) of amphibians, reptiles, birds, and mammals, exoskeletons support the tissues and give shape to the bodies of invertebrates. Exoskeletons offer some other advantages. Serving as a suit of armor, they are excellent protection against predators. Also, because they completely cover an animal’s tissues, exoskeletons prevent them from drying out. In addition, exoskeletons serve as points of attachment for muscles, providing animals with more leverage and mechanical advantage than an endoskeleton can offer. That is why a tiny shrimp can cut a fish in half with its claw or lift an object 50 times heavier than its own body.
Despite all their good points, exoskeletons have some drawbacks. They are heavy, so the only animals that have been successful with them …

Differences in Terrestrial and Aquatic Plants

Even though plants that live in water look dramatically different from terrestrial plants, the two groups have a lot in common. Both types of plants capture the Sun’s energy and use it to make food from raw materials. In each case, the raw materials required include carbon dioxide, water, and minerals. The differences in these two types of plants are adaptations to their specific environments.
Land plants are highly specialized for their lifestyles. They get their nutrients from two sources: soil and air. It is the job of roots to absorb water and minerals from the soil, as well as hold the plant in place. Essential materials are transported to cells in leaves by a system of tubes called vascular tissue. Leaves are in charge of taking in carbon dioxide gas from the atmosphere for photosynthesis. Once photosynthesis is complete, a second set of vascular tissue carries the food made by the leaves to the rest of the plant. Land plants are also equipped with woody stems and branches that …

Mollusks: Gastropods, Bivalves, and Cephalopods

The mollusks are a large group of arthropods that have a variety of outward appearances and include animals such as clams, octopuses, and snails. Because of their tremendous range of structures and styles, mollusks are divided into three groups: gastropods, bivalves, and cephalopods. Unlike their plainer terrestrial relatives, marine species of mollusks have extravagant forms that tend toward elaborately shaped shells and bright colors.
Even though the group is diverse, members share some common traits. The group’s name, mollusk, literally means “soft bodied” and describes one of their primary characteristics. In addition to soft bodies, mollusks are also characterized by a foot that is used for locomotion. Internally, mollusk organs are covered with a thin tissue called the mantle. In some species the mantle secretes the shell and one or more defensive chemicals, such as ink, mucus, or acid.
A mollusk feeds with a file-like rod of muscle called the radula. This tongue-like organ is c…