Unit B Section B1 Introduction Characteristics of Living Things
Completion requirements
Section 1: The characteristics of living things and the functions they perform.
Unit B: Section 1 – Introduction
Figure B.S.1.1 – The blue whale is the largest animal on Earth.
Figure B.S.1.2 – Tropical glass frogs have transparent skin.
Figure B.S.1.3 – The okapi is an animal closely related to the giraffe, even though it has zebra-like skin.
Scientists estimate that Earth contains over 8 million different species of living things. However, only about 2 million species have been discovered. Most organisms appear very different from each other, even though they are all made of cells.
Some organisms are very large. The blue whale is the largest animal on Earth, at 30 metres long. That is approximately the length of three school buses! Blue whales are bigger than the largest dinosaurs that ever lived on Earth. On the other hand, the tiniest living things are one-celled bacteria, too small to see with the unaided eye.
Most animals have interesting adaptations very different from human adaptations. A lizard can regrow its tail, which is useful for survival if its tail is ripped off by a predator. Octopuses have three hearts to pump blood down and up their eight legs. Cows have four stomachs to digest tough grasses.
Many animals have interesting skin coverings. The okapi is an animal related to a giraffe, but it looks like it has zebra legs. The okapi’s striped legs camouflage it in the rainforest. Glass frogs have transparent skin, which makes them blend in with their backgrounds.
What unusual organisms do you know about?
Watch More
Amazing Animal Facts
This video shows ten unusual animals with interesting adaptations.
This video shows ten unusual animals with interesting adaptations.
Blue whales are the largest animal on Earth, but they are not the largest living organism on Earth. Watch this video to find out more about the largest organism on Earth.
As of 2016, there are 7.1 billion humans on Earth. That’s a huge number, but it seems small compared to the number of some other organisms on Earth. Watch this video to learn more.
Words to Think About:
Check out the word cloud below. It pictures the important words that you are going to learn in this section. Watch for these words, and combinations of these words, as you read. When you see them highlighted, you can click on them to learn more about
what the word means. You can also visit the course glossary and read definitions for all of these words.
Lessons in This Section
Lesson B1: What is a Living Thing?
Key Question – What characteristics must an object have, to be alive?
Lesson B2: Structures and Functions
Key Question – What adaptations help keep different organisms alive?
Lesson B3: Cells Working Together as Organs
Key Question – How do organ systems work together to perform important functions?
Reading and Materials for This Section
Science in Action 8
Reading: Pages 84–97
Materials Lists for Unit:
Figure B.S.1.4 – Extremophile bacteria can live in hot acidic geothermal springs.
Figure B.S.1.5 – Both large and small organisms can live in extremely cold Antarctica.
Figure B.S.1.6 – Tardigrades are also known as water bears.
Extremophiles
Some organisms are extremophiles. "Extremo" means “extreme” and “phile” means “loving”. Extremophiles are organisms that thrive in harsh, extreme environments, where most other species cannot survive.
Most extremophiles are tiny organisms such as bacteria. Archaebacteria are extremophiles that have been found in boiling hot acidic geothermal pools, such as in Yellowstone National Park. Archaebacteria have also been found near hydrothermal vents, or underwater volcanoes, in the ocean.
Scientists hypothesize that the first organisms on Earth were extremophiles. 3.5 billion years ago, Earth had no atmospheric oxygen and experienced many hot volcanic eruptions. However, extremophile bacteria formed and could thrive in hot hydrothermal vents on the ocean floor.
There are also extremophiles that can live at very cold temperatures. Scientists have discovered living bacteria buried in Antarctic ice. Tardigrades, or water bears, are another tiny extremophile organism. Tardigrades can survive at both hot and extremely cold temperatures. They can withstand high pressure and deadly radiation. Tardigrades have even been put into outer space without any protection, and survived!
Some organisms are extremophiles. "Extremo" means “extreme” and “phile” means “loving”. Extremophiles are organisms that thrive in harsh, extreme environments, where most other species cannot survive.
Most extremophiles are tiny organisms such as bacteria. Archaebacteria are extremophiles that have been found in boiling hot acidic geothermal pools, such as in Yellowstone National Park. Archaebacteria have also been found near hydrothermal vents, or underwater volcanoes, in the ocean.
Scientists hypothesize that the first organisms on Earth were extremophiles. 3.5 billion years ago, Earth had no atmospheric oxygen and experienced many hot volcanic eruptions. However, extremophile bacteria formed and could thrive in hot hydrothermal vents on the ocean floor.
There are also extremophiles that can live at very cold temperatures. Scientists have discovered living bacteria buried in Antarctic ice. Tardigrades, or water bears, are another tiny extremophile organism. Tardigrades can survive at both hot and extremely cold temperatures. They can withstand high pressure and deadly radiation. Tardigrades have even been put into outer space without any protection, and survived!
Watch More
Living Extreme
Watch this video to learn more about bacteria that thrive in hot geothermal pools.
Watch this video to learn more about bacteria that thrive in hot geothermal pools.
The existence of extremophiles on Earth means that life could exist in other harsh environments in the universe. Watch this video to learn more.
Watch this video to find out how extremophile habitats on Earth are clues to where life might exist on other planets.
Tardigrades, or water bears, are strange-looking extremophiles. Watch this video to learn more about tardigrades.