table of contents – pages iii
DESCRIPTION
Table of Contents – pages iii. Unit 1: What is Biology? Unit 2: Ecology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time Unit 6: Viruses, Bacteria, Protists, and Fungi Unit 7: Plants Unit 8: Invertebrates Unit 9: Vertebrates Unit 10: The Human Body. - PowerPoint PPT PresentationTRANSCRIPT
Unit 1: What is Biology?Unit 2: EcologyUnit 3: The Life of a CellUnit 4: GeneticsUnit 5: Change Through TimeUnit 6: Viruses, Bacteria, Protists, and FungiUnit 7: PlantsUnit 8: InvertebratesUnit 9: VertebratesUnit 10: The Human Body
Unit 1: What is Biology?
Chapter 1: Biology: The Study of LifeUnit 2: Ecology Chapter 2: Principles of Ecology Chapter 3: Communities and Biomes Chapter 4: Population Biology Chapter 5: Biological Diversity and ConservationUnit 3: The Life of a Cell Chapter 6: The Chemistry of Life Chapter 7: A View of the Cell Chapter 8: Cellular Transport and the Cell Cycle Chapter 9: Energy in a Cell
Unit 4: Genetics
Chapter 10: Mendel and Meiosis
Chapter 11: DNA and Genes
Chapter 12: Patterns of Heredity and Human Genetics
Chapter 13: Genetic Technology
Unit 5: Change Through Time Chapter 14: The History of Life Chapter 15: The Theory of Evolution Chapter 16: Primate Evolution Chapter 17: Organizing Life’s Diversity
Unit 6: Viruses, Bacteria, Protists, and Fungi
Chapter 18: Viruses and Bacteria
Chapter 19: Protists
Chapter 20: Fungi
Unit 7: Plants
Chapter 21: What Is a Plant?
Chapter 22: The Diversity of Plants
Chapter 23: Plant Structure and Function
Chapter 24: Reproduction in Plants
Unit 8: Invertebrates
Chapter 25: What Is an Animal?
Chapter 26: Sponges, Cnidarians, Flatworms, and Roundworms
Chapter 27: Mollusks and Segmented Worms
Chapter 28: Arthropods
Chapter 29: Echinoderms and Invertebrate Chordates
Unit 9: Vertebrates Chapter 30: Fishes and Amphibians
Chapter 31: Reptiles and Birds
Chapter 32: Mammals
Chapter 33: Animal Behavior
Unit 10: The Human Body
Chapter 34: Protection, Support, and Locomotion
Chapter 35: The Digestive and Endocrine Systems
Chapter 36: The Nervous System
Chapter 37: Respiration, Circulation, and Excretion
Chapter 38: Reproduction and Development
Chapter 39: Immunity from Disease
Sponges, Cnidarians, Flatworms, and Roundworms
What Is an Animal?
Sponges, Cnidarians, Flatworms, and Roundworms
Mollusks and Segmented Worms
Arthropods
Echinoderms and Invertebrate Chordates
Chapter 26 Sponges, Cnidarians, Flatworms, and Roundworms
26.1: Sponges
26.1: Section Check
26.2: Cnidarians
26.2: Section Check
26.3: Flatworms
26.3: Section Check
26.4: Roundworms
26.4: Section Check
Chapter 26 Summary
Chapter 26 Assessment
What You’ll Learn
You will identify and compare and contrast the characteristics of sponges, cnidarians, flatworms, and roundworms.
You will describe and evaluate the significance of sponge, cnidarian, flatworm, and roundworm adaptations.
• Relate the sessile life of sponges to their food-gathering adaptations.
Section Objectives:
• Describe the reproductive adaptations of sponges.
• Sponges are asymmetrical aquatic animals that have a variety of colors, shapes, and sizes.
• Many are bright shades of red, orange, yellow, and green.
What is a sponge?What is a sponge?
What is a sponge?What is a sponge?
• Although sponges do not resemble more familiar animals, they carry on the same life processes as all animals.
• Sponges are classified in the invertebrate phylum Porifera, which means “pore bearer.”
• Most live in marine biomes, but about 150 species can be found in freshwater environments.
Sponges are pore-bearersSponges are pore-bearers
• Sponges are mainly sessile organisms.
• Because most adult sponges can’t travel in search of food, they get their food by a process called filter feeding.
Sponges are pore-bearersSponges are pore-bearersWater out
Centralcavity
Waterin
Sponges are pore-bearersSponges are pore-bearers
• Filter feeding is a method in which an organism feeds by filtering small particles of food from water that pass by or through some part of the organism.
Water out
Centralcavity
Waterin
A SpongeA SpongeOsculum
Pore cellEpithelial-like cells
Collar cells
AmoebocyteDirection of water flow through pores
Spicules
Cell organization in spongesCell organization in sponges
• For some sponge species, if you took a living sponge and put it through a sieve, not only would the sponge’s cells be alive and separated out, but these cells would come together to form new sponges.
• It can take several weeks for the sponge’s cells to reorganize themselves.
Cell organization in spongesCell organization in sponges• Many biologists hypothesize that sponges
evolved directly from colonial, flagellated protists, such as Volvox.
Volvox
Cell organization in spongesCell organization in sponges
• More importantly, sponges exhibit a major step in the evolution of animals—the change from unicellular life to a division of labor among groups of organized cells.
Reproduction in spongesReproduction in sponges
• Sponges can reproduce asexually and sexually.
• Depending on the species, asexual reproduction can be by budding, fragmentation, or the formation of gemmules.
Reproduction in spongesReproduction in sponges• An external growth, called a bud, can
form on a sponge.
• If a bud drops off, it can float away, settle, and grow into a sponge.
• Sometimes, buds do not break off. When this occurs, a colony of sponges forms.
• Often, fragments of a sponge break off and grow into new sponges.
Reproduction in spongesReproduction in sponges
• Some freshwater sponges produce seedlike particles, called gemmules, in the fall when waters cool.
• The adult sponges die over the winter, but the gemmules survive and grow into new sponges in the spring when waters warm.
Reproduction in spongesReproduction in sponges
• Most sponges reproduce sexually.
• Some sponges have separate sexes, but most sponges are hermaphrodites. A hermaphrodite (hur MAF ruh dite) is an animal that can produce both eggs and sperm.
Reproduction in spongesReproduction in sponges• Eggs and sperm form from amoebocytes.
• During reproduction, sperm released from one sponge can be carried by water currents to another sponge, where fertilization can occur.
Reproduction in spongesReproduction in sponges• Fertilization in sponges may be either external
or internal.
• A few sponges have external fertilization—fertilization that occurs outside the animal’s body.
• Most sponges have internal fertilization, in which eggs inside the animal’s body are fertilized by sperm carried into the sponge with water.
Spermcells
Larvae
Eggcell
Flagella
New sponge
Reproduction in spongesReproduction in sponges
• In sponges, the collar cells collect and transfer sperm to amoebocytes.
• The amoebocytes then transport the sperm to ripe eggs.
Support and defense systems in spongesSupport and defense systems in sponges
• Sponges are soft-bodied invertebrates, that can be found at depths of about 8500 m.
• Their internal structure gives them support and can help protect them from predators.
Support and defense systems in spongesSupport and defense systems in sponges• Some sponges have sharp, hard spicules
located between the cell layers.
• Spicules may be made of glasslike material or of calcium carbonate.
Spicules
Support and defense systems in spongesSupport and defense systems in sponges
• Other sponges have an internal framework made of silica or of spongin, a fibrous protein-like material.
• Sponges can be classified according to the shape and makeup of their spicules and/or frameworks.
Support and defense systems in spongesSupport and defense systems in sponges
• Besides sharp spicules, some sponges may have other methods of defense.
• Some sponges contain chemicals that are toxic to fishes and to other predators.
Question 1
What is the major evolutionary step in animals that sponges exhibit?(TX Obj 2; 4B, 8C, 10A, 10B)
Sponges are the first animals to exhibit the change from a unicellular life to a division of labor among groups of organized cells.
Question 2In sponges, where do fertilized eggs develop into zygotes? (TX Obj 2; 4B, 8C, 10A, 10B)
D. in the jelly between the cell layersC. in the collar cells B. in the pore cells A. in the sponge’s osculum
The answer is D, in the jelly between the cell layers.
Question 3How many layers of cells make up a sponge?(TX Obj 2; 8C)
D. fiveC. four B. three A. two
The answer is A, two.
Section Objectives
• Sequence the stages in the life cycle of a cnidarian.
• Analyze the relationships among the classes of cnidarians.
• Evaluate the adaptations of cnidarians for obtaining food.
• Cnidarians (ni DARE ee uns) are a group of invertebrates made up of more than 9000 species of jellyfishes, corals, sea anemones, and hydras.
What is a cnidarian?What is a cnidarian?
• They can be found worldwide, and all but a few cnidarians live in marine biomes.
• A cnidarian’s body is radially symmetrical. It has one body opening and is made up of two layers of cells.
Body structureBody structure
Cavity
Bud
Disc Outer cell layer
Jellylike layer
Inner cell layer
Tentacle
Mouth
Body structureBody structure Mouth
Cavity
Bud
Disc Outer cell layer
Jellylike layer
Inner cell layer
Tentacle• The two cell layers are organized into tissues with specific functions.
• The inner layer is adapted mainly to assist in digestion.
• Because a cnidarian’s body is only two layers of cells, no cell is ever far from water.
• Oxygen dissolved in water can diffuse directly into body cells.
• Carbon dioxide and other wastes can move out of a cnidarian’s body cells directly into the surrounding water.
Body structureBody structure
• Cnidarians display a remarkable variety of colors, shapes and sizes. Some can be as small as the tip of a pencil.
A CnidarianA Cnidarian
• Most cnidarians have two distinct body forms during their life cycles.
• A polyp is the sessile form of a cnidarian. Its mouth is surrounded by tentacles.
• Examples of polyps include sea anemones, corals, and hydras.
• A medusa is the free-swimming form of a cnidarian.
A CnidarianA Cnidarian
• It possesses an umbrella-shaped, floating body, called a bell, with the mouth on its underside.
Tentacles
A CnidarianA Cnidarian Tentacles
Nematocyst before discharge
Nematocyst after discharge
Bud
Mouth
Tentacles
Prey
• Most cnidarians undergo a change in body form during their life cycles.
Body formBody form
Polyp
Medusa
Body formBody form• There are two body forms, the polyp
and the medusa.
Polyp
Medusa
• In cnidarians, one body form may be more observable than the other. In jellyfishes, the medusa is the body form usually observed.
• The polyp is the familiar body form of hydras.
Body formBody form
• All cnidarians have the ability to reproduce sexually and asexually.
Reproduction in cnidariansReproduction in cnidarians
• Sexual reproduction occurs in only one phase of the life cycle.
• It usually occurs in the medusa stage, unless there is no medusa stage then the polyp can reproduce sexually.
Reproduction in cnidariansReproduction in cnidarians
Male Female
Eggs Sexual Reproduction
Fertilization
Blastula
Larva
PolypBud
Asexual Reproduction
• The most common form of reproduction in cnidarians can be illustrated by the life cycle of a jellyfish.
Reproduction in cnidariansReproduction in cnidarians
• Even though these two stages alternate in a cnidarian’s life cycle, this form of reproduction is not alternation of generations as in plants.
• In plants, one generation is diploid and the other is haploid. However, both cnidarian medusae and polyps are diploid animals.
Reproduction in cnidariansReproduction in cnidarians
Asexualreproduction
Male FemaleMedusae
Sperm
Egg
Sexualreproduction
Larva
Polyp
• Cnidarians are predators that capture or poison their prey using nematocysts.
Digestion in cnidariansDigestion in cnidarians
• A nematocyst (nih MA tuh sihst) is a capsule that contains a coiled, threadlike tube.
• The tube may be sticky or barbed, and it may contain toxic substances.
• Nematocysts are located in stinging cells that are on tentacles.
• Once captured by nematocysts, prey is brought to the mouth by contraction of the tentacles.
Digestion in cnidariansDigestion in cnidarians
Polyp
Medusa
Mouth
Gastrovascular cavity
Mouth
Digestion in cnidariansDigestion in cnidarians
• The inner cell layer of cnidarians surrounds a space called a gastrovascular (gas troh VAS kyuh lur) cavity.
• Cells adapted for digestion line the gastrovascular cavity and release enzymes over captured prey. Any undigested materials are ejected back out through the mouth.
Hydra eating daphnia
• A cnidarian has a simple nervous system without a control center, such as a brain like that of other animals.
Nervous system in cnidariansNervous system in cnidarians
• In cnidarians, the nervous system consists of a nerve net that conducts impulses to and
from all parts of the body.
• The impulses from the nerve net cause contractions of musclelike cells in the two cell layers.
There are four classes of cnidarians:
Diversity of CnidariansDiversity of Cnidarians
• Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa. Cubozoans once were classified as scyphozoans.
• The class Hydrozoa includes two groups—the hydroids, such as hydra, and the siphonophores, including the Portuguese man-of-war.
Most hydrozoans form coloniesMost hydrozoans form colonies
• Most hydroids are marine animals that consist of branching polyp colonies formed by budding, and are found attached to pilings, shells, and other surfaces.
• The siphonophores include floating colonies that drift about on the ocean’s surface.
Most hydrozoans form coloniesMost hydrozoans form colonies
• The Portuguese man-of-war, Physalia, is an example of a siphonophore hydrozoan colony.
• Each individual in a Physalia colony has a function that helps the entire organism survive.
• The fragile and sometimes luminescent bodies of jellyfishes can be beautiful.
Scyphozoans are the jellyfishesScyphozoans are the jellyfishes
• Some jellyfishes are transparent, but others are pink, blue, or orange.
• The medusa form is the dominant stage in this class.
• The gastrovascular cavity of scyphozoans has four internal divisions.
Scyphozoans are the jellyfishesScyphozoans are the jellyfishes
• Like other cnidarians, scyphozoans have musclelike cells in their outer cell layer
that can contract. When these cells contract together, the bell contracts, which propels the animal through the water.
• Anthozoans are cnidarians that exhibit only the polyp form.
Most anthozoans build coral reefsMost anthozoans build coral reefs
• All anthozoans have many incomplete divisions in their gastrovascular cavities.
Sea Anemone
Most anthozoans build coral reefsMost anthozoans build coral reefs
• Sea anemones are anthozoans that live as individual animals, and are thought to live for centuries.
Sea Anemone
• Corals are anthozoans that live in colonies of polyps in warm ocean waters around the world.
Most anthozoans build coral reefsMost anthozoans build coral reefs
• They secrete protective, cuplike calcium carbonate shelters around their soft bodies.
• Colonies of many coral species build the beautiful coral reefs that provide food and shelter for many other marine species.
• Corals that form reefs are known as hard corals.
Most anthozoans build coral reefsMost anthozoans build coral reefs
• Other corals are known as soft corals because they do not build such structures.
• The living portion of a coral reef is a thin, fragile layer that grows on top of the shelters left behind by previous generations.
Most anthozoans build coral reefsMost anthozoans build coral reefs
• Although corals are often found in relatively shallow, nutrient-poor waters, they thrive because of their symbiotic relationship with microscopic, photosynthetic protists called zooxanthellae (zoh oh zan THEH lee).
Most anthozoans build coral reefsMost anthozoans build coral reefs
• The zooxanthellae produce oxygen and food that the corals use, while using carbon dioxide and waste materials produced by the corals.
Most anthozoans build coral reefsMost anthozoans build coral reefs
• These protists are primarily responsible for the bright colors found in coral reefs.
• Because the zooxanthellae are free-swimming, they sometimes leave the corals.
Most anthozoans build coral reefsMost anthozoans build coral reefs
• Corals without these protists often die.
• The earliest fossil evidence for sponges dates this group to late in the Precambrian, about 650 million years ago.
Origins of Sponges and CnidariansOrigins of Sponges and Cnidarians
• The earliest known cnidarians also date to the Precambrian, about 630 million years ago.
Origins of Sponges and CnidariansOrigins of Sponges and Cnidarians
• The earliest coral species were not reef builders, so reefs cannot be used to date early cnidarians.
Origins of Sponges and CnidariansOrigins of Sponges and Cnidarians
• The larval form of cnidarians resembles protists, and because of this, scientists consider cnidarians to have evolved from protists.
Which of the following features is NOT common to both sponges and cnidarians?(TX Obj 2; 4B, 8C, 10A, 10B)
Question 1
D. reproduce both sexually and asexually C. sessile B. radial symmetry A. body made up of two layers of cells
The answer is B.
Explain the difference between the ways cnidarians and sponges take in food.(TX Obj 2; 4B, 8C, 10A, 10B)
Question 2
AnswerSponges passively filter food particles from the water when the particles flow through the sponge. Cnidarians actively seek food with tentacles that capture or paralyze the prey and take it to the cnidarian’s mouth for ingestion.
Explain how each of the two forms in the figure below benefits from contractions of muscle-like cells caused by impulses from its nerve net. (TX Obj 2; 4B, 8C, 10A,10B)
Question 3
Polyp
Medusa
Mouth
Gastrovascular cavity
Mouth
In the sessile polyp form, cell contractions cause tentacles to move prey toward the mouth. In the free-swimming form, cell contractions help the medusa to swim and find food.
Polyp
Medusa
Mouth
Gastrovascular cavity
Mouth
Which of the following is NOT true of cnidarian budding? (TX Obj 2; 4B, 8C, 10A, 10B)
Question 4
D. it is part of asexual reproduction
C. it produces haploid organisms
B. it produces clones of the parents
A. it can form colonies of individuals
The answer is C. Budding produces diploid organisms.
• Distinguish between the structural adaptations of parasitic flatworms and free-living planarians.
Section Objectives:
• Explain how parasitic flatworms are adapted to their way of life.
• The least complex worms belong to the phylum Platyhelminthes (pla tee HEL min theez).
What is a flatworm?
• These flatworms are acoelomates with thin, solid bodies.
Planarian
What is a flatworm? • There are approximately 14,500 species of
flatworms found in marine and freshwater environments and in moist habitats on land.
Planarian
• The most well-known members of this phylum are the parasitic tapeworms and flukes, which cause diseases in other animals, among them frogs and humans.
What is a flatworm?
• The most commonly studied flatworms in biology classes are the free-living planarians.
• Most of a planarian’s nervous system is located in its head—a characteristic common to other bilaterally symmetrical animals.
Nervous control in planarians
Nerve cell mass
Nerve cell mass
Nervous control in planarians
• Some flatworms have a nerve net, and others have the beginnings of a central nervous system.
• A planarian’s nervous system includes two nerve cords that run the length of the body.
Nervous control in planarians
GangliaEyespots
Nerve cord
Muscle cells
Nervous control in planarians • It also includes eyespots that can detect
the presence or absence of light and sensory cells that can detect chemicals and movement in water.
GangliaEyespots
Nerve cord
Muscle cells
• At the anterior end of the nerve cord is a small swelling called a ganglion (plural, ganglia). The ganglion receives messages from the eyespots and sensory pits, then communicates with the rest of the body along the nerve cords.
Nervous control in planarians
Ganglia• Messages from the nerve
cords trigger responses in a planarian’s muscle cells.
• Like many of the organisms studied in this chapter, most flatworms including planarians, are hermaphrodites.
Reproduction in planarians
• During sexual reproduction, individual planarians exchange sperm, which travel along special tubes to reach the eggs.
• Fertilization occurs internally. The zygotes are released in capsules into the water, where they hatch into tiny planarians.
Reproduction in planarians
• Planarians have many characteristics common to all species of flatworms.
A Planarian
• The bodies of planarians are flat, with both a dorsal and a ventral surface. All flatworms have bilateral symmetry.
A Planarian
HeadEyespots
Sensory cells
Extended pharynx
Flame cellCilia
Mouth
Digestive tract
Nucleus
CiliaExcretory system
• Planarians also can reproduce asexually.
Reproduction in planarians
• When a planarian is damaged, it has the ability to regenerate, or regrow, new body parts. Regeneration is the replacement or regrowth of missing body parts.
• If a planarian is cut horizontally, the section containing the head will grow a new tail, and the tail section will grow a new head.
Reproduction in planarians
Reproduction in planarians • Thus, a planarian that is damaged or cut into
two pieces may grow into two new organisms—a form of asexual reproduction.
• A planarian feeds on dead or slow-moving organisms.
Feeding and digestion in planarians
• It extends a tube-like, muscular organ, called the pharynx (FAHR inx), out of its mouth. Enzymes released by the pharynx begin digesting food outside the animal’s body.
Extended pharynx
• Food particles are sucked into the digestive tract, where they are broken up.
Feeding and digestion in planarians
• Cells lining the digestive tract obtain food by endocytosis.
• Food is thus digested in individual cells.
• A parasite is an organism that lives on or in another organism and depends upon that host organism for its food.
Feeding and digestion in parasitic flatworms
• Parasitic flatworms have mouthparts with hooks that keep the flatworm firmly attached inside its host.
Hooks
ScolexSucker
Proglottid
Mature proglottidwith fertilized eggs
• They do not need to move to seek out or find food.
Feeding and digestion in parasitic flatworms
• Parasitic flatworms do not have complex nervous or muscular tissue.
• The body of a tapeworm is made up of a knob-shaped head called a scolex (SKOH leks), and detachable, individual sections called proglottids.
Tapeworm bodies have sections Hooks
ScolexSucker
Proglottid
Mature proglottidwith fertilized eggs
Tapeworm bodies have sections • A proglottid (proh GLAH
tihd) contains muscles, nerves, flame cells, and male and female reproductive organs.
Hooks
ScolexSucker
Proglottid
Mature proglottidwith fertilized eggs
• Some adult tapeworms that live in animal intestines can be more than 10 m in length and consist of 2000 proglottids.
Tapeworm bodies have sections
• A fluke is a parasitic flatworm that spends part of its life in the internal organs of a vertebrate, such as a human or sheep.
The life cycle of a fluke
• It obtains its nutrition by feeding on cells, blood, and other fluids of the host organism.
The life cycle of a fluke
Adult flukes
Embryos released
Larva
Snail host
Larva
Human host
• Blood flukes of the genus Schistosoma cause a disease in humans known as schistosomiasis.
The life cycle of a fluke
• Schistosomiasis is common in countries where rice is grown.
• Blood flukes are common where the secondary host, snails, also are found.
In order to survive and reproduce, a parasite must have a _______. (TX Obj 2; 4B, 8C, 10A, 10B)
Question 1
D. host
C. scolex
B. proglottid
A. pharynx
The answer is D, host.
Explain the way planarians can reproduce asexually. (TX Obj 2; 4B, 8C, 10A, 10B)
Question 2
When a planarian is damaged, it can regenerate new body parts. It can also regenerate new organisms if cut into separate pieces.
• Compare and contrast the structural adaptations of roundworms and flatworms.
Section Objectives:
• Identify the characteristics of four roundworm parasites.
• Roundworms belong to the phylum Nematoda.
What is a roundworm?
• They are widely distributed, living in soil, animals, and both freshwater and marine environments.
• Most roundworm species are free-living, but many are parasitic.
Roundworm
• Roundworms are tapered at both ends.
What is a roundworm?
• They have a thick outer covering, which they shed four times as they grow, that protects them in harsh environments.
MouthIntestine Anus
Round bodyshape
• They lack circular muscles but have lengthwise muscles.
What is a roundworm?
• As one muscle contracts, another muscle relaxes. This alternating contraction and relaxation of muscles causes roundworms to move in a thrashing fashion.
• Roundworms have a pseudocoelom and are the simplest animals with a tubelike digestive system.
What is a roundworm?
• Roundworms have two body openings—a mouth and an anus.
MouthIntestine Anus
Round bodyshape
What is a roundworm?
• The free-living species have well-developed sense organs, such as eyespots, although these are reduced in parasitic forms.
MouthIntestine Anus
Round bodyshape
• Approximately half of the described roundworm species are parasites, and about 50 species infect humans.
Diversity of Roundworms
• Infection by Ascaris (ASS kuh ris) is the most common roundworm infection in humans.
Roundworm parasites of humans
• Children become infected more often than adults do.
• Eggs of Ascaris are found in soil and enter a human’s body through the mouth.
• The eggs hatch in the intestines, move into the bloodstream, and eventually to the lungs, where they are coughed up, swallowed, and begin the cycle again.
Roundworm parasites of humans
• Pinworms are the most common human roundworm parasites in the United States.
Roundworm parasites of humans
• Pinworms are highly contagious because eggs can survive for up to two weeks on surfaces.
• Its life cycle begins when live eggs are ingested. They mature in the host’s intestinal tract.
Roundworm parasites of humans
• Female pinworms exit the host’s anus—usually as the host cell sleeps—and lay eggs on nearby skin.
• These eggs fall onto bedding or other surfaces.
• Trichinella causes a disease called trichinosis (tri keh NOH sis).
Roundworm parasites of humans
• This roundworm can be ingested in raw or undercooked pork, pork products, or wild game.
Trichinella
• Hookworm infections are common in humans in warm climates where they walk on contaminated soil in bare feet.
Roundworm parasites of humans
• Hookworms cause people to feel weak and tired due to blood loss.
• Nematodes can infect and kill pine trees, cereal crops, and food plants such as potatoes.
Roundworm parasites of other organisms
• They are particularly attracted to plant roots and cause a slow decline of the plant.
• They also can infect fungi and can form symbiotic associations with bacteria.
Roundworm parasites of other organisms
• Nematodes also can be used to control pests.
Which of the following is NOT a feature of roundworms? (TX Obj 2; 4B, 8C, 10A, 10B)
Question 1
D. scolex
C. outer covering that can be shed
B. anus
A. pseudocoelom
The answer is D, scolex.
Which of the following parasites embeds itself inside the host’s muscle tissue?(TX Obj 2; 4B, 8C, 10A, 10B)
Question 2
D. Pinworms
C. Ascaris
B. Trichinella
A. Tapeworms
The answer is B. Trichinella is found in pork muscle tissue and can invade the muscle tissue of humans who eat undercooked infected pork.
• A sponge is an aquatic, sessile, asymmetrical, filter-feeding invertebrate.
Sponges
• Sponges are made of four types of cells. Each cell type contributes to the survival of the organism.
• Most sponges are hermaphroditic with free-swimming larvae.
• All cnidarians are radially symmetrical, aquatic invertebrates that display two basic forms: medusa and polyp.
Cnidarians
• Cnidarians sting their prey with cells called nematocysts located on their tentacles.
• The three primary classes of cnidarians include the hydrozoans, hydras; schyphozoans, jellyfishes; and anthozoans, corals and anemones.
• Flatworms are acoelomates with thin, solid bodies. They are grouped into three classes: free-living planarians, parasitic flukes, and tapeworms.
Flatworms
• Planarians have simple nervous and muscular systems. Flukes and tapeworms have structures adapted to their parasitic existence.
• Roundworms are pseudocoelomate, cylindrical worms with lengthwise muscles, relatively complex digestive systems, and two body openings.
Roundworms
• Roundworms can be parasites of plants, fungi, and animals, including humans.
Question 1Which of the following is NOT a method of asexual reproduction in sponges?(TX Obj 2; 4B, 8C, 10A, 10B)
D. flagellated larvae
C. gemmule formation
B. fragmentation
A. budding
The answer is D. Flagellated larvae result from sexual reproduction.
Question 2In hermaphroditic sponges, eggs and sperm form from _______. (TX Obj 2; 4B, 8C, 10A, 10B)
D. collar cells
C. amoebocytes
B. epithelial cells
A. larvae
The answer is C, amoebocytes.
Amoebocyte
Question 3
Describe the symbiotic relationship between corals and zooxanthellae. (TX Obj 2; 4B, 8C, 10A, 10B)
Zooxanthellae produce oxygen and food that the corals use. The corals produce carbon dioxide and waste materials that the zooxanthellae use.
Question 4The cnidarians with many incomplete divisions in their gastrovascular cavities are the _______.(TX Obj 2; 4B, 8C, 10A, 10B)
D. Siphonophores
C. Anthozoans
B. Hydrozoans
A. Scyphozoans
The answer is C, Anthozoans.
Question 5The medusa is the body form usually observed in _______.(TX Obj 2; 4B, 8C, 10A, 10B)
D. Anthozoans
C. Siphonophores
B. Hydrozoans
A. Scyphozoans
The answer is A, Scyphozoans.
Question 6How is a secondary host involved in the life cycle of a tapeworm?(TX Obj 2; 4B, 8C, 10A, 10B)
AnswerThe eggs of the tapeworm hatch when a secondary host eats them.
Question 7The secondary host for the blood fluke is a _______. TX Obj 2; 4B, 8C, 10A, 10B)
D. dogC. snail
B. sheep
A. human
The answer is C, snail.
Question 8The simplest animals with a tube-like digestive system are _______.(TX Obj 2; 4B, 8C, 10A, 10B)
D. Anthozoans
C. Hydrozoans
B. Platyhelminthes
A. Nematodes
The answer is A, Nematodes.
Roundworm
Question 9
Which of the following is not a roundworm infection in humans?(TX Obj 2; 4B, 8C, 10A, 10B)
D. ascaris
C. pinworm
B. ringworm
A. hookworm
The answer is B. Ringworm is a fungal infection.
Photo CreditsPhoto Credits
• Digital Stock
• Ward's Natural Science Est.
• Kip Evans/NOAA
• Florida Keys National Marine Sanctuary/NOAA
• Carolina Biological Supply Co.
• Dr. John Crites
• David M. Dennis
• Alton Biggs
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