Crossword Puzzle for Classification of Living Things
Topics 1-3:  Introduction, Principles of Classification,
and Kingdom to Subphylum


1. The genus and species of all living humans.
4. Anatomical features that have the same form or function in different species that have no known common ancestor. An example would be the wings of a bird and a butterfly.
6. A group of closely related species. It is the category immediately above species.
8. The subphylum of chordates in which the notochord is replaced by a more complex spinal chord late in the embryonic stage of development. The spinal chord is protected by a segmented vertebral column of cartilage and/or bone.
10. An evolutionary mechanism that occurs when some individuals of a population are better able to adapt to their environment and, subsequently, produce more offspring. Nature, in effect, selects which members of a population are fit to survive long enough to reproduce.
12. The term for the two Latin name categories (genus and species) used in the Linnaean classification system to designate each type of organism. The term you are looking for literally means "two names" in Latin.
13. Anatomical structures in different species that are similar due to descent from a common ancestor that had them.
14. The expansion and diversification of an evolving group of organisms as they adapt to new ecological niches. This is the process by which one species evolves into two or more species. It occurs as a result of different populations becoming reproductively isolated from each other, usually by adapting to different environments.
16. Similar anatomical structures in different species that were not present in their common ancestor.
17. The largest natural population of organisms that can potentially interbreed to produce fertile offspring.
19. The phylum of animals that is characterized by soft, unsegmented bodies that are usually, but not always, enclosed in hard shells. They also usually have at least one strong foot that helps them move. Octopi, squids, snails, slugs, clams, and other shellfish are members of this phylum.
20. The development of a similar anatomical feature in distinct species lines after divergence from a common ancestor that did not have the initial trait that led to it. The common ancestor is usually more distant in time than is the case with parallel evolution.
21. The category or level in the Linnaean classification system in which organisms are primarily distinguished on the basis of overall basic body plan or organization (e.g., soft, unsegmented bodies in contrast to external skeletons along with jointed bodies and limbs).
22. The phylum of animals that have elongated bilaterally symmetrical bodies. In some phase of their life cycle, they have a notochord and gill slits or pouches. Members of this phylum also often have a head, a tail, and a digestive system with an opening at both ends of the body. This phylum includes fish, amphibians, reptiles, birds, mammals, and 2 invertebrate subphyla (tunicates and lancelets). Humans are members of this phylum.
23. A similar evolutionary development in different species lines after divergence from a common ancestor that had the initial anatomical feature that led to it. This is thought to be due primarily to the independent species lines experiencing the same kinds of natural selection pressures.
24. The category or level in the Linnaean system of classification in which organisms are primarily  distinguished on the basis of cellular organization and methods of nutrition. Whether they are single- or multiple-celled and whether they absorb, ingest, or produce food are also critical factors.
25. The process of naming, describing, and classifying organisms into different categories on the basis of evolutionary relationships.


2. The biological order that includes all species of monkeys, apes, and humans. The word was derived from a Latin word meaning “first.”
3. Organs in some animals that are used to obtain oxygen under water. In the case of humans, other mammals, birds, and reptiles, lungs replace rudimentary forms of these organs after the embryonic stage of development. Frogs replace them with lungs in the transition from tadpoles to adults. Fish retain them all of their lives.
5. The phylum of animals that is characterized by external skeletons as well as jointed bodies and limbs. Insects, spiders, centipedes, lobsters, and crabs are members of this phylum.
7. A rudimentary internal skeleton made of stiff cartilage that runs lengthwise under the dorsal surface of the body of some animals. Generally, there is a single hollow nerve chord on top of it. Among humans and the other vertebrates, this structure is replaced by a more complex skeleton following the embryonic stage of development.
9. The characteristic of left and right sides of the body generally being mirror images of each other. If there are two functionally similar body parts, they are usually found roughly equidistant from the center line, parallel to each other.
11. The kingdom that includes organisms that produce new cell matter out of inorganic material by photosynthesis. They do not have the ability to move around their environment except by growing or being transported by wind, water, or other external forces.
15. The kingdom that includes organisms that do not produce their own food but must eat other organisms to obtain it. They have nerves and muscles that aid in controlled movement around their environment.
17. The level of classification immediately below phylum and above class in the Linnaean classification system.
18. The classification system in use by the biological sciences today to classify all living things. It was invented by and subsequently named after an 18th century Swedish botanist.

Copyright © 2005 by Dennis O'Neil. All rights reserved.