The main groups of living things
A frog, a sardine and a spider live in different places and move in different ways. Within each kingdom we need another level of organisation: the main groups.
Vertebrates
When we eat a sardine we find a central backbone, and when we touch our own back we feel a row of hard bones, but when we look at an earthworm or a jellyfish we see that its whole body is soft: which internal structure divides animals into two great models of organisation?
Name the five groups of vertebrates and give an example of an animal for each. Also state the characteristic shared by all vertebrates, which gives the group its name.
Name the five groups of vertebrates and give an example of an animal for each. Also state the characteristic shared by all vertebrates, which gives the group its name.
State which group of vertebrates each animal belongs to and which feature helped you decide: a salmon, a grass snake, an eagle, a toad, and a cow.
State which group of vertebrates each animal belongs to and which feature helped you decide: a salmon, a grass snake, an eagle, a toad, and a cow.
The diagram shows the five groups of vertebrates with a typical trait for each, but one group is missing, marked with "?". State which group it is, describe its defining…
The diagram shows the five groups of vertebrates with a typical trait for each, but one group is missing, marked with "?". State which group it is, describe its defining characteristics, and give two examples of animals from that group.
Invertebrates
Explain what an invertebrate is and name four groups of invertebrates with an example of an animal from each.
Explain what an invertebrate is and name four groups of invertebrates with an example of an animal from each.
How many legs do insects have and how many do arachnids have? Name two animals from each group and point out another visible difference between them.
How many legs do insects have and how many do arachnids have? Name two animals from each group and point out another visible difference between them.
From this list of animals —dog, ant, spider, earthworm, snail, jellyfish, and trout— first separate the vertebrates from the invertebrates. Then, group the invertebrates…
From this list of animals —dog, ant, spider, earthworm, snail, jellyfish, and trout— first separate the vertebrates from the invertebrates. Then, group the invertebrates into insects, arachnids, worms, molluscs, and jellyfish, stating a feature that helped you decide in each case.
Plant groups
Mosses do not have true roots or conducting vessels like those of vascular plants; ferns have roots, stems and leaves, but no seeds. Both reproduce by spores and their fertilisation depends on water.
Seed plants include gymnosperms, such as pines, whose seeds are not enclosed in fruits, and angiosperms, such as the geranium, with flowers and seeds inside fruits. The cones of the pine are neither fruits nor flowers like those of angiosperms.
Explain the difference between mosses, ferns, and flowering plants, and give an example of each group that you could find near where you live. What type of habitat does…
Explain the difference between mosses, ferns, and flowering plants, and give an example of each group that you could find near where you live. What type of habitat does each typically grow in?
Name the main parts of a flowering plant (root, stem, leaves, flower, and fruit) and explain the function of each one.
Name the main parts of a flowering plant (root, stem, leaves, flower, and fruit) and explain the function of each one.
Classifying by kinship, not by where they live
The sea urchin is named after the hedgehog ("urchin" is an old word for it), but one is a marine invertebrate and the other a mammal. Explain what this case shows about…
The sea urchin is named after the hedgehog ("urchin" is an old word for it), but one is a marine invertebrate and the other a mammal. Explain what this case shows about the common names of animals and compare the characteristics of both.
An explorer finds an unknown marine animal: it has a streamlined body, lacks hind limbs, moves by means of flippers, and spends its entire life underwater. However, he…
An explorer finds an unknown marine animal: it has a streamlined body, lacks hind limbs, moves by means of flippers, and spends its entire life underwater. However, he observes that it periodically surfaces to take in air and that it gives birth to live young which it feeds with milk. The explorer notes in his journal: "Because of its shape and because it always lives in water, it is a new species of fish." Refute his conclusion by justifying why it should be classified as a mammal, and predict what type of reproduction, fertilisation, and thermal regulation (homeothermic or poikilothermic) you would expect to find in this animal.
Look at these three animals: the bat, the sparrow, and the dolphin. If we used a classification criterion based exclusively on the medium through which they move, which…
Look at these three animals: the bat, the sparrow, and the dolphin. If we used a classification criterion based exclusively on the medium through which they move, which two animals would you group together? Explain why this criterion is misleading for biologists and justify, by comparing the internal anatomy of their limbs and their mode of reproduction, why the bat is much more closely related to the dolphin than to the sparrow.
Back to the beginning: The sardine (fish) and the frog (amphibian) are vertebrates because they have an internal backbone, while the spider is an invertebrate (arachnid) with an exoskeleton and eight legs, showing that real kinship defines the group, not the environment where they live or how they move.