After completing this chapter you will be able to: - describe key unifying and distinguishing features of organisms from the fungi, plant, and animal kingdoms
- explain how these kingdoms contribute to, and are dependent on, the biodiversity of life on Earth
- analyze some of the consequences of human influences and interactions on the biodiversity and health of ecosystems
- explain the significant changes that have occurred in fungi, plants, and animals as they have evolved over time
- make biological drawings of representative species
What Organisms Dominate the Land?
Life on land poses many challenges to living things. Unlike many aquatic environments, the conditions on land vary greatly. The most complex organisms—fungi, plants, and animals—have overcome these challenges and flourished. Most fungi and almost all plant species live in terrestrial ecosystems. And, although many animals are aquatic, the great majority of animal species are terrestrial.
In aquatic ecosystems, water temperatures are usually very stable. They may change by no more than a few degrees in a day and range from 20 °C to 0 °C in an entire year. In terrestrial ecosystems, temperature can change by 10 °C in 10 min and range from 40 °C to —40 °C in a year. Fungi, plants, and animals have responded to these variable conditions with adaptations that allow them to survive temperature fluctuations. Some organisms become dormant and others migrate. Some, including humans, spend extra energy to maintain a constant body temperature regardless of the surrounding environment.
Water is essential for all life but is not always available on land. Water loss through evaporation is a constant concern for terrestrial organisms. They deal with these challenges with waterproof coverings and internal water storage. Some plants even collect rainwater in cup-shaped leaves.
On land, organisms must be able to support their own mass against the force of gravity, without the buoyant force of water. To help them do so, they have developed supporting structures such as internal skeletons, external skeletons, and strong woody tissues. In animals, skeletons provide support and also allow mobility, including flight.
Fungi, plants, and animals also adapted to life on land with each other. They have established many relationships: producer and consumer, predator and prey, and symbiotic partnerships.
Humans, as members of the animal kingdom, share many of these adaptations and take part in many interrelationships with other species. Exploring the biodiversity of these three kingdoms offers us many insights into our own biology and the amazing web of life around us.
STARTING POINTS
Answer the following questions using your current knowledge. You will have a chance to revisit these questions later, applying concepts and skills from the chapter.
1. In what ways do you think the life cycles of organisms on land might be different from those in the water?
2. Some organisms are considered "simple," while others are considered "complex." What set of characteristics would you use to distinguish the simple from the complex?
3. The great diversity of life includes species that are adapted to very specific environmental conditions. How do you think changes to those environmental conditions due to climate change or pollution events, such as an oil spill, might impact species?
4. Brainstorm a number of human characteristics that make us well suited for life on land.
The Fungi, Plants, and Animals
KEY CONCEPTS
After completing this chapter you will be able to:
- describe key unifying and distinguishing features of organisms from the fungi, plant, and animal kingdoms
- explain how these kingdoms contribute to, and are dependent on, the biodiversity of life on Earth
- analyze some of the consequences of human influences and interactions on the biodiversity and health of ecosystems
- explain the significant changes that have occurred in fungi, plants, and animals as they have evolved over time
- make biological drawings of representative species
What Organisms Dominate the Land?
Life on land poses many challenges to living things. Unlike many aquatic environments, the conditions on land vary greatly. The most complex organisms—fungi, plants, and animals—have overcome these challenges and flourished. Most fungi and almost all plant species live in terrestrial ecosystems. And, although many animals are aquatic, the great majority of animal species are terrestrial.
In aquatic ecosystems, water temperatures are usually very stable. They may change by no more than a few degrees in a day and range from 20 °C to 0 °C in an entire year. In terrestrial ecosystems, temperature can change by 10 °C in 10 min and range from 40 °C to —40 °C in a year. Fungi, plants, and animals have responded to these variable conditions with adaptations that allow them to survive temperature fluctuations. Some organisms become dormant and others migrate. Some, including humans, spend extra energy to maintain a constant body temperature regardless of the surrounding environment.
Water is essential for all life but is not always available on land. Water loss through evaporation is a constant concern for terrestrial organisms. They deal with these challenges with waterproof coverings and internal water storage. Some plants even collect rainwater in cup-shaped leaves.
On land, organisms must be able to support their own mass against the force of gravity, without the buoyant force of water. To help them do so, they have developed supporting structures such as internal skeletons, external skeletons, and strong woody tissues. In animals, skeletons provide support and also allow mobility, including flight.
Fungi, plants, and animals also adapted to life on land with each other. They have established many relationships: producer and consumer, predator and prey, and symbiotic partnerships.
Humans, as members of the animal kingdom, share many of these adaptations and take part in many interrelationships with other species. Exploring the biodiversity of these three kingdoms offers us many insights into our own biology and the amazing web of life around us.
STARTING POINTS
Answer the following questions using your current knowledge. You will have a chance to revisit these questions later, applying concepts and skills from the chapter.
1. In what ways do you think the life cycles of organisms on land might be different from those in the water?
2. Some organisms are considered "simple," while others are considered "complex." What set of characteristics would you use to distinguish the simple from the complex?
3. The great diversity of life includes species that are adapted to very specific environmental conditions. How do you think changes to those environmental conditions due to climate change or pollution events, such as an oil spill, might impact species?
4. Brainstorm a number of human characteristics that make us well suited for life on land.