Biology chapter 25
Terms in this set (58)
Animals, which are members of the animal kingdom, are multicellular, heterotrophic, eukaryotic organisms whose calls lack cell walls
What characteristics do all animals share?
an organism that lacks a backbone
Invertebrates include all animals that lack a backbone, or a vertebral column. All chordates exhibit 4 characteristics during at least one stage in life: a dorsal, hollow nerve cord; a notochord; a tail that extends beyond the anus; and a pharyngeal pouch
What characteristics distinguish invertebrates and chordates?
animals that have a dorsal, a hollow nerve chord, a notochord, a tail that goes beyond the anus, and pharyngeal pouches
a long supporting rod that runs through the body just below the nerve cord
paired structures in the throat region which is also called the pharynx
chordates with backbones including fish, amphibians, reptiles, birds, and mammals
Like all organisms, animals must maintain homeostasis by gathering and responding to information, obtaining and distributing oxygen and nutrients, and collecting and eliminating carbon dioxide and other wastes. They also reproduce.
What essential functions must animals perform to survive?
negative feedback. The system in which the product or result of a process limits the process itself.
Specialized cells unique to each sense organ that respond to a particular form of sensory stimulation.
Existence of a stable internal environment
Features of animal body plans include levels of organization, body symmetry, differentiation of germ layers, formation of body cavities, patterns of embryological development, segmentation, cephalization, and limb formation
What are some features of animal body plans?
any number of imaginary planes drawn through the center of the body could divide into equal halves
a single imaginary plane divides the body into left and right sides that are mirror images of one another
innermost germ layer
a body cavity that develops within the mesoderm and is completely lined with tissue derived form the mesoderm
a cavity partially lined with mesoderm
a hollow ball of cells like an inflated balloon
the blastopore becomes the mouth
the blastopore becomes the anus, and the mouth is formed from the second opening that develops
the concentration of sense organs and nerve cells at their anterior end
Animal and phyla are typically defined according to adult body plans and patterns of embryological development
How are animal phyla defined?
Body is made up of a series of fused rings; external and internal structures are repeated segment by segment
structures such as legs or antennae protruding from the body
Such fossil evidence indicates that the first animals began evolving long before the cambrian explosion
When did the first animals evolve?
A relatively brief time in geologic history when large, hard-bodied forms of animals with most of the major body plans known today appeared in the fossil record. This burst of evolutionary change occurred about 535-525 million years ago.
The cladogram of nonchordate invertebrates presents current hypotheses about evolutionary relationships among major groups of modern invertebrates. It also indicates the sequence in which some important features evolved.
What does the cladogram of nonchordate invertebrates illustrate?
Have no tissues, no organs and most have no symmetry - name means pore-bearers
radial symmetry, stinging cells, uncephalized
A group of organisms that have jointed appendages, an exoskeleton, bilateral symmetry, and reproduce sexually; insects, arachnids, millipedes and cenitpedes, and crustaceans
(nematodes) have a complete digestive system, two separate sexes, infect either by eggs or larva
A group of often parasitical worms that have bilateral symmetry, a one opening digestive system, and the beginnings of a brain; tapeworm
A type of worm that has a closed circulatory system, nephridia, and a hydrostatic skeleton. examples: (Earthworm, Leeches)
Animal with a muscular mass of tissue called a foot and a multifunctional structure called a mantle
A radially symmetrical invertebrate that lives on the ocean floor and has an internal skeleton
Embryological studies suggest that the most ancient chordates were related to the ancestors of echinoderms.
What are the most ancient chordates?
many mollusks have a free swimming larval stage called this
a strong connective tissue that is softer and more flexible than bone
the nanvertebrate chordates, fishes, amphibians, reptiles, birds, and mammals
What are the six groups of chordates?
The cladogram of chordates presents current hypotheses about relationships among chordate groups. It also shows at which points important vertebrate features, such as jaws and limbs, evolved.
What can we learn by studying the cladogram of chordates?
Sharks have cartilage instead of true bone.
Why aren't sharks related to bony fish?
Cartilage is more flexible and it is used to protect bones.
What is the difference between bone and cartilage?
four limbed vertebrates
In general, a primate is a mammal that has relatively long fingers and toes with nails instead of claws, arms that can rotate around shoulder joints, a strong clavicle, binocular vision, and a well developed cerebrum
What characteristics do all primates share?
the ability to combine visual images from both eyes, providing depth perception and a three dimensional view of the world
Primates in one of these groups look very little like typical monkeys. this group contains the lemurs and lorises. The other group includes tarsiers and the anthropoids, the group that includes monkeys, great apes, and humans
What are the major evolutionary groups of primates?
humanlike primates, include monkeys, great apes, and humans
a tail that can coil tightly enough around a branch to serve as a "fifth hand"
include gibbons, orangutans, gorillas, chimpanzees, and humans
the hominoids in the lineage that led to humans
The skull, neck, spinal column, hip bones, and leg bones of early hominine species changed shape in ways that enabled later species to walk upright
What adaptations enabled later hominine species to walk upright?
a finger that could bend at touch to enable grasping things easier
Many species in our genus existed before our species, Homo sapiens, appeared. Furthermore, at least three other Homo species existed at the same time as early humans
What is the current scientific thinking about the genus Homo?