Module 4-Chapter 17

Invertebrates Vertebrates

Animals

Multicellular ingestive heterotrophs; that is, complex organisms (eukaryotes) that obtain energy and carbon by ingesting food into their bodies and digesting it internally.

Radial symmetry

An animal body plan in which the body can be sliced symmetrically along any number of vertical planes that pass through the center of the animal. Compare bilateral symmetry.

Bilateral symmetry

An animal body plan in which the body can be divided by just one plane passing vertically from the top to the bottom of the animal into two halves that mirror each other. Compare radial symmetry.

Chordates

A large phylum that encompasses all animals with backbones, such as fishes, birds, and mammals.

Notochord

In chordates, a flexible yet rigid rod along the center of the body that is critical for development.

Nerve cord

A solid strand of nervous tissue that we call the spinal cord in humans.

Vertebrate

A chordate that possesses a backbone.

Vertebrae

The strong, hollow sections of the backbone, or vertebral column.

Cartilage

A dense tissue of the skeleton that combines strength with flexibility. It is found almost everywhere that two bones meet and prevents them from grinding together.

Segments

Repeated identical units that make up the body plan of arthropods, annelids, and vertebrates.

Appendages

Body parts with specialized functions that develop in pairs from particular segments of an animal's body.

Mammals

A large class of animals that have body hair, sweat glands, and milk produced by mammary glands.

Eutherians

One of three main groups of mammals, whose members have a placenta and produce offspring that are born in a well-developed state. Compare marsupials and monotremes.

Marsupials

One of three main groups of mammals, whose members have a simple placenta and produce offspring that complete development in their mother's pouch. Compare eutherians and monotremes.

Monotremes

One of three main groups of mammals, whose members lack a placenta and lay eggs. Compare eutherians and marsupials.

Primates

The order of mammals to which humans belong. All primates have flexible shoulder and elbow joints, five functional fingers and toes, opposable thumbs, flat nails, and brains that are large in relation to the body.

Opposable

Able to be placed opposite other digits of the hand or foot. For example, opposable thumbs can be placed opposite each of the other four fingers.

Hominids

The ape family, which includes humans and chimpanzees. All hominids are capable of tool use, symbolic language, and deliberate acts of deception. Compare hominins.

Hominins

The "human" branch of the hominids, including modern humans and extinct relatives such as Neanderthals.

Bipedal

Walking upright on two legs.

Mitochondrial-DNA inheritance

The passing down of DNA from the mitochondria in an egg cell to a new generation. Mitochondrial DNA passes virtually unchanged from mother to child, so it can be tracked from one generation, or one species, to another. Sequencing of mitochondrial DNA can determine how related an individual is to its female ancestors on its mother's side. Compare nuclear-DNA inheritance.

Nuclear-DNA inheritance

The passing down of DNA from the nucleus in an egg or sperm cell to a new generation. Sequencing of nuclear DNA can determine how related an individual is to all of its ancestors, both male and female. Compare mitochondrial-DNA inheritance.