Question

How is the opossum related to you? a. An opossum is an animal, but I am a human. b. An opossum is a mammal, but I am a human. c. An opossum is a marsupial, but I am a placental mammal. d. The opossum and I are both placental mammals.

Short answer

c. An opossum is a marsupial, but I am a placental mammal.

Step-by-step solution

Understand the classification of humans

As humans, we belong to the animal kingdom and have specific classifications based on biology. The main classification for humans is: Kingdom: Animalia, Class: Mammalia, and Subclass: Placentalia (or Eutheria).

Understand the classification of opossums

Opossums are also a part of the animal kingdom, and their specific classifications are: Kingdom: Animalia, Class: Mammalia, and Subclass: Marsupialia (or Metatheria).

Compare the classifications and choose the correct option

Based on the known classifications: a. Although both humans and opossums are part of the animal kingdom, distinguishing one as an animal and the other as a human is not entirely accurate. b. Humans and opossums both belong to the class Mammalia, meaning they are both mammals. This option differentiates humans and opossums based on class, but that is not entirely accurate. c. Opossums belong to the subclass Marsupialia, while humans belong to the subclass Placentalia. Based on this information, this option correctly differentiates between humans and opossums in terms of their biological relationship. d. This option is incorrect because opossums are not placental mammals. They belong to the Marsupialia subclass. So, the correct answer is: c. An opossum is a marsupial, but I am a placental mammal.

Key concepts

Animal Kingdom Taxonomy

Taxonomy is the science of classifying organisms to construct internationally shared classification systems which reflect the genetic relationships between all living things. Within this vast system, the Animal Kingdom, known as Kingdom Animalia, is one of the primary classifications used by taxonomists. This kingdom is subdivided into various phyla, classes, orders, families, genera, and species.

For mammals, the relevant taxonomy levels are:

• Phylum: Chordata - animals with a spinal cord.
• Class: Mammalia - warm-blooded vertebrates with hair or fur and, in females, milk-producing mammary glands.

Understanding taxonomy is crucial as it helps us categorize the immense diversity of life and understand the connections between different species.

Marsupials vs Placental Mammals

Mammalia, the class of animals that includes mammals, is further divided into subclasses, one of which differentiates between marsupials and placental mammals. Marsupials, belonging to the subclass Marsupialia, are notable for giving birth to partially developed offspring that complete their development outside the womb, often in a pouch. Examples include kangaroos, koalas, and opossums.

In contrast, placental mammals, part of the subclass Placentalia, carry their offspring in the womb until a later stage of development. The placenta, an organ unique to this group, facilitates the exchange of nutrients and waste between mother and fetus. Humans, whales, and elephants are examples of placental mammals.

Understanding the distinctions between these two groups is important for recognizing their unique reproductive strategies and biological characteristics.

Biological Relationships

Biological relationships refer to the connections and similarities among living organisms based on their genetic and evolutionary history. Taxonomic classifications indicate these relationships and help us trace the lineage of species.

Through taxonomy, we understand that all mammals share a common ancestor, which leads to the similarities in structure and function, such as the presence of mammary glands and three middle ear bones. Beyond this, subdivisions in the classification system highlight the evolutionary paths different species have taken, such as the divergence of marsupials and placental mammals, helping us to map the tree of life and see how closely related or distantly related different species are to each other.

Taxonomy of Humans and Opossums

Humans and opossums are both classified under the Class Mammalia, signifying that we share some broad characteristics. However, the taxonomy of each follows different paths beyond this level:

• Humans - Subclass: Placentalia, Order: Primates, Family: Hominidae, Genus: Homo, Species: sapiens.
• Opossums - Subclass: Marsupialia, Order: Didelphimorphia, Family: Didelphidae, Genus: Didelphis, Species: virginiana (if we consider the common North American opossum).

While humans and opossums share membership in the mammalian group, their specific taxonomic categories reflect the distinct evolutionary paths leading to the species we see today.

This taxonomy-based perspective helps identify the point at which our evolutionary paths diverged, emphasizing the differences in our reproductive systems and various related adaptations.