Download Unit 4 Part 2 Outline Animal Diversity

Unit 4, Part 1: Animal Diversity
CHAPTER 30: ANIMALS: PART I
30.1 Evolutionary Trends Among Animals
Animals are extremely diverse, but in general they are heterotrophic, typically have the power of
movement or locomotion by means of muscle fibers, are multicellular, have a life cycle in which
the adult is typically diploid, and undergo sexual reproduction and produce an embryo that goes
through development stages. All but one of the 30 animal phyla is invertebrates. Only one
phylum contains vertebrates.
Anatomical Data
Refer to Figure 30.2.
Type of Symmetry
Animals can be asymmetrical, radially symmetrical, or bilaterally symmetrical.
Embryonic Development
Sponges have the cellular level of organization. True tissues appear in the other
animals as they undergo embryological development. Some animals have two
germ layers (ectoderm and endoderm), while some have three (ectoderm,
endoderm, and mesoderm). Animals with three germ layers are either
protostomes or deuterostomes.
30.2 Introducing the Invertebrates
Sponges
Sponges are aquatic. They are multicellular but lack organized tissues. They are filter
feeders. Sponges can reproduce both asexually and sexually.
Cnidarians
Cnidarians are multicellular, tubular, or bell-shaped animals that reside mainly in shallow
coastal waters. They are radially symmetrical and have true tissues.
Cnidarian Diversity
Examples of cnidarians include sea anemone, coral, hydrozoans, and jellyfish.
Hydra
Hydra is a freshwater cnidarian. It has a sac body plan. It has two tissue layers:
ectoderm and endoderm.
30.3 The Trochozoa
The trochozoa are bilaterally symmetrical at least in some stage of their development. As
embryos, they have three germ layers, and as adults, they have the organ level of organization.
Trochozoans are protostomes and include the trochophores, which either have a trochophore larva
today or an ancestor with one in the past.
Flatworms
Flatworms have bilateral symmetry. They also have three germ layers. They are
acoelomates.
Free-Living Flatworms
Freshwater planarians are small, literally flat, worms. They have an excretory
and a nervous system.
Parasitic Flatworms
The parasitic flatworms include the tapeworms and the flukes.
Tapeworms
Tapeworms are endoparasites of various vertebrates, including humans.
They attach to the intestinal wall of the host and feed.
Flukes
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Flukes are all endoparasites of various vertebrates. They are usually
named for the type of vertebrate organ they inhabit.
Rotifers
Rotifers are related to the flatworms and both are trochozoans. Rotifers have a crown of
cilia, known as the corona, on their heads.
Molluscs
Molluscs include chitons, limpets, slugs, snails, abalones, conchs, nudibranchs, clams,
scallops, squid, and octopuses. They have a true coelom, bilateral symmetry, three germ
layers, the organ level of organization, and a complete digestive tract.
Unique Characteristics of Molluscs
All molluscs have a body composed of at least three parts: the visceral mass, the
foot, and the mantle.
Gastropods
Gastropods include nudibranchs, conchs, and snails. The foot is ventrally
flattened.
Cephalopods
Cephalopods include octopuses, squid, and nautiluses. The foot has evolved into
a funnel or siphon about the head.
Bivalves
Bivalves include clams, mussels, oysters, and scallops. Their shells have two
parts.
The Visceral Mass
The clam has an open circulatory system and a heart. It also has a
nervous system and a digestive system.
Comparison
Refer to Table 30.2 for a comparison of a clam, squid, and land snail.
Annelids
Annelids are segmented, have a hydrostatic skeleton, and specialization of the digestive
tract.
Polychaetes
Marine annelids are the Polychaeta, which refers to the presence of many setae.
Setae are bristles that anchor the worm or help it move.
Oligochaetes
The oligochaetes, which include earthworms, have few setae per segment.
Segmentation
Segmentation is evidenced by body rings, coelom divided by septa, setae
on most segments, ganglia and lateral nerves in each segment, nephridia
in most segments, and branch blood vessels in each segment.
Reproduction
Earthworms are hermaphroditic.
Comparison with Clam Worm
The comparison of the marine clam worm with the terrestrial earthworm
highlights the manner in which earthworms are adapted to life on land.
Leeches
Leeches have no setae and each body ring has several transverse grooves.
Among their modifications are two suckers.
30.4 The Ecdysozoa
The ecdysozoans are protostomes, as are the trochozoa. The term ecdysis means molting, and
both roundworms and arthropods, which belong to this group, periodically shed their outer
covering.
Roundworms
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Roundworms are nonsegmented worms that are prevalent in almost any environment.
They possess a pseudocoelom.
Ascaris
A female Ascaris is very reproductively prolific. They are most commonly
parasites of humans and pigs.
Other Roundworms
Trichinosis is a fairly serious infection cause by eating pork that is not fully
cooked that contains encysted larvae of the round worm Trichinella spiralis.
Elephantiasis is caused by a roundworm called the filarial worm. Pinworm and
hookworm infections are more common in the United States.
Arthropods
Arthropods are extremely diverse. Over one million species have been discovered and
described. Arthropods have jointed appendages and an exoskeleton made of chitin. They
are segmented and have a well-developed nervous system that includes a brain and a
ventral solid nerve cord. They have a variety of respiratory organs and have reduced
competition through metamorphosis.
Crustaceans
Crustaceans include barnacles, shrimps, lobsters, and crabs. They are named for
their hard shells.
Internal Organs
In the crayfish, the digestive system includes a stomach. The coelom is
reduced to a space around the reproductive system. They have an open
circulatory system. The nervous system is very similar to that of an
earthworm.
Insects
Insects are very numerous and diverse. Insects have a body that is divided into a
head, a thorax, and an abdomen. The head bears sensory antennae, a pair of
compound eyes, and several simple eyes. The mouthparts are adapted for the type
of food. Wings may be present.
Internal Organs
In the grasshopper, there is an excretory system, a respiratory system,
and a circulatory system.
Reproduction and Development
Metamorphosis is a change in form and physiology that occurs as an
immature stage, called a larva, becomes an adult.
Comparison with Crayfish
A comparison of a grasshopper with a crayfish reveals the adaptations to
a terrestrial environment.
Arachnids
The arachnids include scorpions, spiders, ticks, and mites. They have six pairs of
appendages.
CHAPTER 31: ANIMALS: PART II
31.1 Echinoderms
Chordates are most closely related to the echinoderms as witnessed by their similar
embryological development.
Characteristics of Echinoderms
Echinoderms are all marine animals. They have an endoskeleton and are often radially,
not bilaterally, symmetrical.
Echinoderm Diversity
Echinoderms include sea lilies, feather stars, brittle stars, and sea cucumbers.
Sea Stars
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Sea stars have a five-rayed body with an oral and an aboral side. Locomotion
depends on a water vascular system. They do not have a respiratory, excretory,
or circulatory system. Sea stars reproduce both asexually and sexually.
31.2 Chordates
To be classified as a chordate, an animal must have, at some time during its life history, a dorsal
supporting rod called a notochord, a dorsal tubular nerve cord, pharyngeal pouches, and a
postanal tail.
Evolutionary Trends among the Chordates
Several characteristics, including vertebrate, jaws, lungs, jointed appendages, a land
existence, and reproduction suitable for land, distinguish each group of animals from the
preceding one.
Nonvertebrate Chordates
In nonvertebrate chordates the notochord never becomes a vertebral column. Tunicates
and lancelets are nonvertebrate chordates.
31.3 Vertebrates
Vertebrates have a strong, jointed endoskeleton. The embryonic notochord is generally replaced
by a vertebral column. A high degree of cephalization is accompanied by sense organs.
Vertebrates have efficient respiration and excretion, and a closed circulatory system.
Fishes: First Jaws, Then Lungs
The first vertebrates were jawless fishes. Today there are three living groups of fishes:
jawless fishes, cartilaginous fishes, and bony fishes. The latter two groups have jaws.
Jawless Fishes
Jawless fishes have smooth, scaleless skin and no jaws or paired fins. These
include the hagfishes and lampreys.
Cartilaginous Fishes
Cartilaginous fishes include the sharks and the skates. They have skeletons of
cartilage instead of bone.
Bony Fishes
Bony fishes are by far the most numerous and diverse of all the vertebrates.
Bony fishes are divided into ray-finned and lobe-finned fishes.
Amphibians: Jointed Appendages
Amphibians live both on land and in the water. These include frogs, toads, newts, and
salamanders. Amphibians usually have four limbs, eyelids, ears, and a voice-producing
larynx. Adult amphibians usually have small lungs.
Reptiles: Amniotic Egg
The reptiles include the dinosaurs, now extinct, turtles, alligators, snakes, and lizards.
Reptiles are adapted for life on land. Fertilization is internal and the female lays leathery,
flexible, shelled eggs.
Feathered Reptiles
Birds lay a hard-shelled amniotic egg. They have scales on their legs and feathers.
Diversity of Birds
The majority of birds are able to fly. Some are flightless.
Anatomy and Physiology of Birds
Nearly every anatomical feature of a bird can be related to its ability to fly. Birds
are endothermic and contain a four-chambered heart.
Mammals: Hair and Mammary Glands
Mammals evolved from the reptiles. The chief characteristics are body hair and milkproducing mammary glands.
Monotremes
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Monotremes are mammals that have a cloaca as a common chamber for feces,
excretory wastes, and sex cells. They lay hard-shelled amniotic eggs.
Marsupials
The young of marsupials begin their development inside the female’s body, but
they are born in a very immature condition. Newborns crawl up into a pouch on
their mother’s abdomen, attach to the nipples of mammary glands, and continue
to develop.
Placental Mammals
The vast majority of living mammals are placental mammals. The
extraembryonic membranes have been modified for internal development within
the uterus of the female. The mammalian brain is well-developed and enlarged
due to the expansion of the cerebral hemispheres. Mammals also have
differentiated teeth.
Primates
Primates are members of the order Primates. They are adapted to an arboreal life (living
in trees). Primate limbs are mobile, and the hands and feet both have five digits each.
The evolutionary trend among primates is toward a larger and more complex brain.
31.4 Human Evolution
All primates share one common ancestor and the other types of primates diverged from the
human line of descent over time. Humans are most closely related to African apes.
Evolution of Humanlike Hominins
To be a hominin, a fossil must have an anatomy suitable for standing erect and walking
on two feet.
Australopithecines
Australopithecines is the possible direct hominid ancestors for humans. There
were robust and gracile forms.
Evolution of Early Homo
Early Homo species all have a brain size that is 600 cc or greater, their jaw and teeth
resemble those of humans, and tool use is in evidence.
Homo habilis and Homo rudolfensis
H. habilis used tools. The speech centers of the brain are enlarged.
Homo ergaster and Homo erectus
Compared to H. habilis, H. ergaster had a larger brain and a flatter face. These
were the first to use fire, and both types used more advanced tools.
Homo floresiensis
It appears that this type coexisted with modern Homo sapiens.
Evolution of Modern Humans
The multiregional continuity hypothesis proposes that modern humans arose from archaic
humans in essentially the same manner but in different locations. The out-of-Africa
hypothesis proposes that modern humans evolved only in Africa and then migrated to
Europe and Asia.
Neandertals
The Neandertal brain was slightly larger than that of Homo sapiens. They had massive
brow ridges and wide, flat noses. Evidence suggests that Neandertals were culturally
advanced.
Cro-Magnon
Cro-Magnons are the oldest fossils to be designated Homo sapiens. They had a
thoroughly modern appearance. They were the first to have language.
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