Adaptations: behavioural, physiological and anatomical

In a nutshell

Certain adaptations of an organism help it survive in its habitat. These adaptations can be physiological, behavioural or anatomical. Marsupials and placental mammals have both evolved from a common ancestor to be well adapted to their habitats.

Adaptations

Definition

Characteristics of an organism that increase its chances of survival and reproduction. They can be behavioural, physiological or anatomical.

Adaptation	Description	Examples
Behavioural	The way an organism acts (behaves) can increase its chance of survival.	Scorpions dance before mating as this ensures they attract a mate of the same species. This increases the chance of successful mating. Many species of birds migrate to warmer climates during winter to avoid living in cold conditions and the associated problems.
Physiological	Processes that occur inside an organism's body can increase its chance of survival.	Desert animals produce very little sweat and small amounts of concentrated urine to ensure they do not lose too much water. Some bacteria produce antibiotics that can kill other bacteria in the area. This increases their chance of survival as there would be less competition.
Anatomical	Structural features of an organism's body can increase its chance of survival.	Arctic foxes have white fur so they cannot be seen against the snow. This protects them from predators and allows them to sneak up on prey. Animals that live in hot environments like camels have a thin layer of fat and a large surface area to volume ratio. This helps them lose heat and stay cool.

Marsupials vs. placental mammals

There are three different groups of mammals: marsupials, placental mammals and egg-laying monotremes. Marsupials diverged from placental mammals millions of years ago, both of these types of mammals have evolved separately ever since.

	Marsupials	Placental mammals
Gestation (pregnancy) period	Short.	Long.
Placenta	Don't develop a full placenta.	Develop a placenta during pregnancy, this allows the exchange of nutrients and waste between the foetus and mother.
Birth	Are born early in development and climb into the mother's pouch. Here, they are provided with milk and this allows development to continue.	Are born fully developed.
Example	Kangaroos.	Humans.

Marsupial and placental moles

Marsupial and placental moles have changed over time via convergent evolution. This means they aren't closely related but they have evolved similar characteristics independently of one another. They have similar anatomical features because they are both evolved to live in similar environments which are tunnels in the ground.

Examples

Some shared anatomical features include:

1.	Small/non-existent eyes as they do not need to see underground.
2.	No external ears which provides them with a streamlined head for burrowing.
3.	Scoop-shaped and powerful front paws for digging.
4.	Specialised claws for digging.
5.	A tube-shaped body and cone-shaped head which makes it easier to push through soil.