Chapter 23: Invertebrate Diversity

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					                                    Chapter 23: Invertebrate Diversity
                                                Resources

Student Edition Labs
Feeding Hydra p. 709
Anatomy of a Clam p. 714

Options for Inquiry
Anatomy of a Sea Star p. 722
Anatomy of an Annelid p. 723

Lab Binder
Additional Investigation: Evolution of the Coelom p. 13-16
Challenge Lab: Cardiovascular System of Mudworms p. 92-96

Power Presentation
Presentation Presentations Chapter 23

Media Gallery
Body Plan Symmetry
Shared Body Structures
Lion’s Mane Jellyfish
Flamingo Tongue Snail
Power Notes

Video
Diversity of Invertebrates

Animated Biology
Digestive Tract Formation
Shared Body Structures

Transparencies
Hox Gene Expression T93
Protostome and Deuterostome Development T94
Phylogeny of Animals T95
Sponge Anatomy T96
Cnidarian Anatomy T97
Flatworm Anatomy T98
Mollusk Anatomy T99
Annelid Anatomy T100
Roundworm T101
Echinoderm Anatomy T102

www.classzone.com
Chapter 23: Invertebrate Diversity
23.1: Animal Characteristics
Objectives: Describe how animals comprise a diverse kingdom.
            Identify the defining characteristics of animals.
Warm Up: If no one had gone before you and you had to classify all living things, where would you
start?
Words to Know: Collagen, Homeotic, Homeobox

Animals are Diverse
     More than 1 million species of animals have been described so far, and scientists predict that tens of
       millions more have yet to be discovered.
     Animals are remarkably diverse.
     Animals are found nearly everywhere on Earth, including places where plants and fungi do not live.
     They are the dominant herbivores, predators and detritivores in most ecosystems.
What ecological factors determine where certain animals are found?
Characteristics of ALL Animals
     All animals are multicellular heterotrophs.
             Animals must eat.
             Animals have complex systems.
     Animal cells are supported by Collagen.
             Collagen is a three stranded protein unique to animals.
             Ex: skin, bone, ligaments, fingernails and hair are all made of collagen.
     Animals are Diploid and usually reproduce Sexually
             All individual animals are Diploid and produce offspring that are diploid.
     Most animals have Hox Genes
             Homeotic genes are a class of genes that control early development in animals.
             Every homeotic gene has a specific sequence of 180 nucleotides called Homeobox or Hox genes.
             These genes define the head-to-tail pattern of development in animal embryos.
How are homeotic and Hox genes related?
23.1 Assessment p. 698 (1-5)

23.2: Animal Diversity
Objectives: Describe the unique body plans of the animal phyla.
             Describe the criteria used to group animals.
             Explain how genetics reveals the evolutionary history of animals.
Warm Up: How would you describe the symmetry of your body? How would you describe the symmetry
of a starfish? How would you describe the symmetry of a sponge?
Words to Know: Vertebrate, Invertebrate, Phylum Bilateral Symmetry, Radial Symmetry, Protostome,
Deuterostome.

Unique Body Plans
    A Vertebrate is an animal with an internal segmented backbone.
    Vertebrates are the most obvious animals around us.
    Vertebrates make up only 5% of all animals.
    Invertebrates are animals without backbones.
    Invertebrates make up 95% of all animals.
Animal Phyla
    Scientists now use shared characters to divide animals into more than 30 major groups.
    Each group, or Phylum, of animals is defined by structural and functional characteristics that are
      different from every other animal group.
    Some phyla have thousands of species (like mollusks) and some have fewer.
Homeobox Genes and Body Plans
    Differences in body plans result from differences in the expression of Homeobox genes.
    These instructions start a chain reaction that turns on all other genes that define the adult form – where
      limbs go, how many eyes develop, the location of the gut and so on.
    All the animal phyla first appeared during the Cambrian explosion.
    The trigger is believed to be sharp increases in oxygen.
How are Hox genes related to the diversity of body plan?

Animals are Grouped by Different Criteria
Body Plan Symmetry
      Symmetry refers to how similar an object is across a central axis.
      Animals with Bilateral Symmetry can be divided equally along only one plane, which splits an animal
        into mirror-image sides.
               Ex: humans, crabs, dogs etc…
               Bilateral animals have distinct heads (anterior) and tails (posterior).
               They also have distinct backs (dorsal) and bellies (ventral).
      Animals with Radial Symmetry have body parts arranged in a circle around a central axis.
               Ex: Sea urchins
Tissue Layers
      Bilateral animals have 3 distinct layers of tissue (triploblastic).
      These layers are the: ectoderm (outer layer), endoderm (inner layer) and mesoderm (middle layer).
               The ectoderm forms the skin and the brain and nervous system.
               The endoderm lines the animal’s gut.
               The mesoderm develops into tissues and organs.
      Most Radial Animals have only 2 distinct layers.
      These layers are the: Endoderm and Ectoderm.
               Since they have no mesoderm, they do NOT have complex internal tissue.
Developmental Patterns
      Animals are separated into two major divisions: the protostomes and the deuterostomes.
      Development between these two is different.
First Opening of the Digestive Cavity
      In Protostomes, the mouth is formed first and the anus second.
      In Deuterostomes, the first opening forms the anus, and the mouth is formed second.
Gut Cavity Formation
      In Protostomes, the gut cavity is formed from separation in the mesoderm.
      In deuterostomes, the gut cavity forms from pouches created by the fold in the gut tube.
Cleavage Pattern
      In Protostomes, early cell divisions lead to an eight-celled embryo in a twisted arrangement called
        spiral cleavage.
      In Deuterostomes, cells divide into eight-celled embryos with cells that are lined up one atop the other
        in an arrangement called radial cleavage.
Is the symmetry of the human body bilateral or radial?
Evolutionary History of Animals
     Sponges, which lack tissues, are the simplest members of the animal kingdom, followed by animals with
       two tissue layers, such as jellyfish and corals.
     Two major phylogenic branches are the protostomes and deuterostomes.
Protostomes
     Protostomes are further divided into the Lophotochozoa (flatworms, annelids and mollusks) and
       Ecdysozoa (roundworms and arthropods).
Deuterostomes
     Deuterostomes include member of the Echinodermata (sea stars and sand dollars) and the Chordata
       (fish, amphibians, reptiles, birds, and mammals).
Unexpected Evolutionary Relationships
     Originally roundworms and earthworms were grouped together, but it has been discovered that
       roundworms are more closely related to insects.
     Arthropods and earthworms are not related at all.
     Flatworms have even been divided into two groups.
Unanswered Questions
     The current phylogenetic tree for animals is in NO way finished.
     A large number of questions still need to be answered.
     As molecular technologies improve, and an increased number of species are studied, scientists will be
       able to put together a more accurate picture of the invertebrate evolutionary tree.
What evidence was used to reorganize the animal kingdom?
23.2 Assessment p. 704 (1-6)

23.3: Sponges and Cnidarians
Objectives: Describe the characteristics and anatomy of sponges and cnidarians.
Warm Up: What characteristics must sponges have to be included in the animal kingdom?
Words to Know: Sessile, Filter Feeder, Polyp, Medusa, Mesoglea, Nematocyst, Gastrovascular Cavity

Sponges
    Sponges have long been considered the most primitive animals on Earth because their body plan is that
      of an early multicellular organism.
    Sponge fossils more than 570 million years old make them one of the most ancient groups of known
      animals.
    Molecular evidence connects them to a group of protists called choanoflagellates, which are considered
      the ancestors of all animals.
Sponge Characteristics
    Sponges lack muscles and nerve cells.
    They are Sessile – unable to move from where they are attached.
    They secrete toxic substances to prevent other sponges from growing into their area and protect
      themselves from predators.
    Some of these toxins have been used to develop medicines.
Sponge Reproduction
    Reproduce both sexually (two parents) and asexually (one parent).
    In sexual reproduction, eggs and sperm are released into the water and fertilization occurs there.
    The fertilized egg develops into free-swimming larva that attaches to a surface where it develops into its
      adult form.
    Asexual reproduction occurs through Budding – a piece of the adult sponge breaks off and floats in the
      water until it finds somewhere to attach and grow into an adult form.
Sponge Anatomy
    Sponges do NOT have mouths.
    They are Filter Feeders who eat by straining particles from the water.
    All sponge bodies are made up of two layers of cells that cover a framework of collagen-like fibers
      called Spongin.
    The skeleton is reinforced with hard calcium or silicon-based crystals called Spicules.
    Sponges have 3 types of specialized cells:
             Pinacocytes – thin and leather cells that form the sponge’s outer layer.
             Choanocytes (collar cells) – for the inner layer of the sponge.
                      Each has a long flagellum surrounded by a collar of tiny hair-like structures.
                      These cells pull water through the sponge by beating their flagella and are used for
                       feeding.
             Amoebocytes – mobile cells that help absorb and digest food particles.
                      They also transport oxygen and water in the sponge.
What characteristics make sponges the simplest animals?

Cnidarians
    The oldest existing animals that have specialized tissue.
Cnidarian Characteristics
    Cnidarians have 2 body forms: Polyp and Medusa
            Polyps are cylindrical tubes with mouth and tentacles facing upward.
                    Ex: corals and hydras
            Medusas are umbrella-shaped with their mouth and tentacles on the underside.
                    Ex: jellyfish.
    Many cnidarian species alternate between the two forms during their life cycle.
    Both have Radial Symmetry.
Cnidarian Reproduction
    Cnidarians can reproduce sexually and asexually.
    Polyps reproduce asexually by budding.
    In the medusa form, cnidarians reproduce sexually by releasing gametes into the water.
    The fertilized egg develops into larva called planula that develops into the polyp stage.
Cnidarian Anatomy
    Cnidarian bodies have two tissue layers separated by a non-cellular jelly-like material called Mesoglea.
    The outer layer of tissue is made up of 3 types of cells: Contracting cells, Nerve cells, and Cnidocytes.
            Contracting Cells – cover the surface of the cnidarian and contain muscle fibers.
            Nerve Cells – send sensory information around the animal and coordinate muscular contractions.
            Cnidocytes – specialized cells that contain stinging structures used for defense and capturing
             prey.
                    Found all over the cnidarian’s body, but most are on tentacles.
    The stinging structure in jellyfish and anemones is the Nematocyst.
             A Nematocyst is a capsule containing a thin, coiled, harpoon-shaped, tubule with a poisonous
              barb at one end.
     When feeding, the nematocysts pull the prey toward the animal’s mouth into the inner tissue layer called
       the Gastrovascular Cavity.
Cnidarian Classes
     Anthozoa – sea anemones and corals (no medusa stage, ONLY polyps)
     Hydrozoa – fire corals, man-of-war, and hydras. (alternate between polyp and medusa stages)
     Scyphozoa – jellyfish (very short polyp stage or none at all, mainly Medusa)
     Cubozoa – box jellyfish and sea wasps (well developed eyes)
How do the polyp and medusa forms differ?
23.3 Assessment p. 708 (1-5)
Feeding Hydras p. 709

23.4: Flatworms, Mollusks and Annelids
Objectives: Identify the characteristics of flatworms and annelids.
            Identify the characteristics of the phylum Mollusca and its seven classes.
Warm Up: What are some examples of mollusks? What common annelid can you dig up from your
garden at home? What kind of symmetry do these animals exhibit?
Words to Know: Complete Digestive Tract, Radula, Hemocoel, Segmentation, Coelom

Flatworms
    Flatworms have a solid body and an incomplete or absent gut.
    A flatworm’s shape is the direct result of having NO circulatory system.
    They move oxygen through their cells by diffusion.
    Three groups of flatworms include: Planarians, Flukes and Tapeworms
Planarians
    Planarians are free-living, nonparasitic, flatworms.
    Have a head with eyespots and a simple brain built of a cluster of nerve tissue.
    They have bands of muscle to help them twist their bodies.
Flukes
    Are parasites that feed off the body fluids of other animals.
    Have a mouth with a pharynx that opens into a gut cavity.
    Many have life cycles involving more than one host.
Tapeworms
    Are parasites that live in vertebrate guts.
    Have a small head with suckers or hook used to attach to the host.
    They have NO gut, but absorb nutrients from the digested food in which they live.
    Segments with eggs will break off the tapeworm and get excreted with the host’s feces.
    Common in dogs, cats and humans.
How are planarians different from flukes and tapeworms?

Mollusks
   Mollusks have a complete digestive tract.
   A Complete Digestive Tract consists of two openings – a mouth and anus – at opposite end of a
      continuous tube.
   Animals with complete digestive tracts can eat continuously.
Mollusk Anatomy
   Radula – is a filelike feeding organ. Mollusks eat by scraping their radula over their food.
   Mantle – is an area of tissue covering the internal organs. It also secretes a hard calcium-based shell
      that protects the animal from predators.
   Ctenidia – fall gills found in a pocket of the mantle tissue called the mantle cavity. Helps absorb
      oxygen.
   While the gills contain blood vessels, blood is also pumped through the hemocoel – spaces between cells
      within the tissues.

Classes of Mollusks
    There are 7 classes of mollusks.
    The majority are found within 3 major classes: the gastropods, pelecypods (bivalve), and cephalopods.
Gastropoda
    Includes snails, nudbranchs, abalones, and limpets.
    Live in both land a aquatic ecosystems.
    Means “belly foot”
    Have one or no shell.
Pelecypoda (Bivalves)
    Includes clams, oysters, mussels, and scallops.
    Have a soft body protected by two hard shells hinged together.
    Most are filter feeders in marine environments.
Cephalopoda
    Includes squid, octopus, nautilus and cuttlefish.
    Well-developed nervous system and eyes.
    Are Carnivorous
    Name means “head foot”
Scaphopoda
    Called the tusk shells.
    Live at the bottom of water bodies.
Polyplacophora
    Chitons – animals with overlapping shells.
Aplacophora
    Small worm-like animals that do NOT have shells.
    Live in deep water.
Tryblidia
    Were believed to be extinct, but reappeared in 1952.
    Little is known about these marine mollusks that live in deep water.
Mollusk Reproduction
    Use a variety of reproductive strategies.
    Some, like snails, are hermaphrodites containing both male and female reproductive organs.
             Reproduction usually involves cross-fertilization.
             Just before mating, the impregnating snail fires a “love dart” into the other.
    All use sexual reproduction.
What common features are shared by ALL mollusks?
Quick Lab: Anatomy of a Clam p. 714
Annelids
     All annelids share more similarities in their body plans than mollusks.
     Three groups of annelids – earthworms, marine worms, and leeches – are characterized by segmentation.
     Segmentation refers to the repeated sections of an annelid’s body that contain a complex set of body
       structures.
Annelid Anatomy
     A typical annelid segment contains parts of the digestive tract, nerve cord, and blood vessels that carry
       blood to the worm’s tissues.
     Annelids have a closed circulatory system, where blood travels in a closed circuit inside blood vessels.
     Each body segment also contains organs that collect and excrete wastes.
     The Coelom is a fluid-filled space that is completely surrounded by muscle.
     It is divided into sections called septa.
Annelid Diet
     Earthworms and Marine Worms eat organic waste material.
     Earthworms secrete digest material called castings, into the soil and help replenish nutrients.
     Leeches are blood feeders or predators that feed on invertebrates and vertebrates.
Annelid Reproduction
     Annelid reproduction can be asexual or sexual.
     Asexual reproduction results from fragmentation – the breaking off of a piece of the body that becomes
       a new individual.
     Earthworms are also hermaphrodites and reproduce much like snails.
     Marine worms have male and females that reproduce to form larva.
In what ways are annelids different from mollusks?
23.4 Assessment p. 715 (1-6)

23.5: Roundworms
Objectives: Identify characteristics of roundworms.
            Recognize the role of roundworms as parasites.
Warm Up: What is the common name of the parasite that can infect dogs?
Words to Know: Cuticle, Pseudocoelom

Roundworms (Nematodes)
    Are the most numerous kinds of animals with more than 15,000 species that vary in size from less than
     1mm to over 10 m in length.
    All roundworms have a tough exoskeleton called a cuticle.
    The Cuticle is made of chitin and must be shed whenever the animal grows larger.
Roundworm Anatomy
    A roundworm is cylindrical with a blunt head and tapered tail.
    Muscle in roundworms is laid out lengthwise.
    The fluid-filled space in roundworms is called a Psuedocoelom because it is not completely lined by
     muscle.
    They do NOT have circulatory or respiratory systems.
    The digestive system includes a mouth, pharynx, intestine and anus.
Roundworm Reproduction
    Reproduce sexually.
    Larvae develop from eggs laid by the female.
Parasitic Roundworms
     Many roundworms are parasitic that specialize in feeding off of most living things.
     Roundworms that infect humans include: hookworms, pinworms, and guinea worms.
     Hookworms feed off of blood and burrow in through bare feet.
     Pinworms infect the gut.
     Guinea worms are found in the gut and connective tissue of the host and are typically found in
       contaminated drinking water.
Why might most parasitic roundworms live in the gut of their host?
23.5 Assessment p. 717 (1-5)

23.6: Echinoderms
Objectives: Describe the symmetry of echinoderms.
            Identify the five classes of echinoderms and describe some of their characteristics.
Warm Up: What type of animal found in tide pools is radially symmetric? What other invertebrate
phylum in this chapter has radial symmetry?
Words to Know: Ossicle, Water Vascular System

Echinoderms
    Adult echinoderms are slow-moving marine animals that have radial symmetry.
    Echinoderm larvae have bilateral symmetry.
Echinoderm Anatomy
    All echinoderms have an internal skeleton made up of many tiny interlocking calcium-based plates
      called Ossicles.
    These ossicles are embedded within the skin.
    Echinoderms have a Water Vascular System, which is a series of water-filled radial canals that extend
      along each arm from the ring canal surrounding the central disk.
    This is used for circulation and for filling the tube feet.
    Tube feet are used to grab objects and move.
Echinoderm Reproduction
    Most reproduce Sexually.
    Sperm and egg are released into the water for fertilization of the egg.
    Some can Regenerate – regrow limbs.

There are 5 Classes of Echinoderms
Feather Stars and Sea Lilies
    Class Crinoidea.
    Can walk with legs but is usually attached to a surface.
Sea Stars
    Class Asteroidea
    Everything from filter feeders to carnivorous predators.
Brittle Stars and Basket Stars
    Class Ophiuroidea.
    Brittle stars have long spindly arms and are fast movers.
    Basket stars have long arms with many branches.
Sea Urchins, Sea Biscuits and Sand Dollars
    Class Echinoidea
    Sea biscuits and sand dollars are covered with tiny projections used for movement and burial.
    Sea Urchins have long sharp spines.
Sea Cucumbers
     Class Holothuroidea.
     Fleshy animals with a long bilateral shape.
     The are sediment feeders.
How do feeding behaviors differ between sea stars and sea cucumbers?
23.6 Assessment p. 720 (1-5)
Correlations Among Invertebrate Data p. 721
Anatomy of a Sea Star p. 722
Anatomy of an Annelid p. 723
www.classzone.com
Chapter Assessment p. 725-727
                                Chapter 24: A Closer Look at Arthropods
                                              Resources

Student Edition Labs
Comparing Arthropods p. 733
Hatching Brine Shrimp p. 739

Options for Inquiry
Daphnia and Heart Rate p. 750
Inside a Crayfish p. 751

Lab Binder
Additional Investigation: Identifying Arthropods in a Decomposer p. 27-31
Forensics Lab: Determining Time of Death Using Entomology p. 84-87
Virtual Lab Worksheet: Insect and Crime Scene Analysis p. 101

Power Presentations
Presentation Chapter 24

Media Gallery
Arachnid Anatomy
Arthropod Types
Compound Fly Eye
Praying Mantis
Power Notes

Video
Evolution and importance of arthropods

Animated Biology
Molting Cicada
Insect Metamorphosis
What Type of Arthropod?

Transparencies
Crustacean Anatomy T103
Arachnid Anatomy T104
Complete Metamorphosis of a Monarch Butterfly T105

www.classzone.com
Chapter 24: A Closer Look at Arthropods
24.1: Arthropod Diversity
Objectives: Describe the adaptive features of arthropods including the exoskeleton.
            Recognize that arthropod diversity evolved over millions of years.
Words to Know: Arthropod, Exoskeleton, Chitin, Appendage, Segmentation, cuticle

Arthropod Characteristics
    An Arthropod is an invertebrate animal with an exoskeleton made of chitin; a series of paired, jointed
      appendages; and segmented body parts.
    An Exoskeleton is an external skeleton that support the animal’s tissues against gravity.
    Most exoskeletons are made out of Chitin – a long organic molecule made of sugars that is arranged in
      layers.
             Chitin protects animals like armor.
    Arthropods also have Jointed Appendages – an extension of an organism’s body (like legs).
    Arthropods can have 6, 8, 10, or hundreds of appendages.
    Segmentation describes how an arthropod’s body parts are divided into similar sections that have each
      evolved for a different function.

Arthropod Groups
    Most arthropods can be placed into four or five groups.
Trilobites
    Now extinct, but were an important part of Paleozoic marine ecosystem for 300 million years.
Crustaceans
    Found in all of the oceans, freshwater streams and land.
    Diverse group that includes: crabs, lobsters, copepods, barnacles, pill bugs, crayfish and shrimp.
Chelicerates
    Includes horseshoe crabs, scorpions, spiders, mites, and ticks.
    These animals share a set of specialized dagger-like mouthparts that are useful for tearing their food.
Insects
    Account for 80% of all known animal species.
    Includes: ants, bees, butterflies, moths, cockroaches, fleas and mosquitoes.
    Most are terrestrial and have 6 legs.
Myriapods
    Centipedes and Millipedes.
How did the evolution of jointed appendages lead to the wide variety of arthropods we see today?

Arthropod Exoskeleton
    The exoskeleton determines how an arthropod lives.
Movement and Growth
    Two types of cuticle plates assist in movement.
Molting
    Arthropod cuticle cannot grow along with the animal, so an arthropod must shed its exoskeleton in a
      process called Molting.
    Before molting an animal secretes a new layer of cuticle that is slightly larger than the old one.
    The animal secretes enzymes to digest and weaken the old cuticle.
    The animal will then crawl out of the old exoskeleton.
    The new exoskeleton is soft and takes time to harden.
    During this time the animal is vulnerable to predators.
Internal Functions
Circulation
     Arthropods have an open circulatory system.
     The exoskeleton of arthropods helps control blood pressure.
Senses
     Most arthropods have sensory organs including: antennae, body hairs, and compound eyes.
How does an exoskeleton make functions such as movement and growth difficult?
Comparing Arthropods p. 733
24.1 Assessment p. 734 (1-6)

24.2: Crustaceans
Objectives: Explain the ecological significance of marine crustaceans.
            Describe crustacean appendages and the main crustacean groups.
Words to Know: Crustacean, Cephalothorax, Abdomen, Carapace, Mandible, filter feeding, sessile.

Crustacean Evolution
     Crustaceans are a group of arthropods that have two distinct body sections, a hard exoskeleton, two pairs
       of antennae, and one pair of appendages per segment.
     Crustacean bodies are made up of two distinct body segments: a cephalothorax and an abdomen.
              The Cephalothorax is the region of an organism in which the head and trunk region are combined
               into one long section.
              The Abdomen refers to the rear portion of the organism.
     The Cephalothorax is covered by a shield-like section called the Carapace, that protects the gills.
Describe how a decrease in marine crustacean populations could affect an ocean ecosystem.
Crustacean Appendages
     All crustacean appendages are homologous structures.
     Crustacean appendages are adapted to an underwater habitat and are essential for survival.
     They have large claws found in crabs and lobsters.
     All crustaceans have Two Pairs of Antennae on their head.
     Crustaceans have Mandibles – highly adapted appendages used to crush and bite food.
     Crustaceans have walking legs.
Give three examples of crustacean appendages and how they are used.
Types of Crustaceans
     Decapods are lobsters, crabs, hermit crabs, king crabs and shrimp and have 10 legs.
     Barnacles are sessile, filter feeders wrapped in a heavily calcified shell.
     Isopods have flattened bodies and seven pairs of legs.
              Also include wood lice and pill bugs.
     Tongue Worms are parasites that live in the lings and nasal passages of vertebrates.
What evidence helped scientists to classify barnacles and tongue worms as crustaceans?
24.2 Assessment p. 738 (1-5)
Hatching Brine Shrimp p. 739
24.3: Arachnids
Objectives: Describe the adaptations and diversity of arachnids.
Words to Know: Chelicerate, Arachnid, Book Lungs, Spiracle, Trachea

Arachnids
     Arachnids are Chelicerates – arthropods that lack antennae and have six pairs of appendages that include
       four pairs of waling legs.
     One specialized set of appendages are the chelicerae or fangs that are used to mash up food.
     A second set of appendages called Pedipalps, are used to grasp and hold prey.
     Chelicerate bodies have two sections: a cephalothorax and an abdomen.
     There are three groups of Chelicerates: sea spiders, horseshoe crabs and Arachnids.
     Arachnids are a terrestrial group of chelicerates characterized by 8 legs, fanglike pincers that inject
       venom and the ability to product silk.
     Arachnids have four different adaptations that reduce water loss:
              Waterproof cuticle.
              Book Lungs – structures built of many thin, hollow sheets of tissue that look like the pages of a
               book and provide a large surface for gas exchange.
              Malpighian Tubules – allow spiders to minimize loss of water while excreting wastes.
              Spiracles – tiny holes on the abdomen that open and close to allow oxygen to enter.
              Trachea then carry oxygen directly to the arachnid’s tissues.
How do the features of an arachnid allow it to live on land?
Arachnids are a diverse Group
     Spiders make up half of the more than 60,000 known arachnid species
     All spiders produce venom.
     Mites, ticks and chiggers are also arachnids.
     Scorpions are also classified with arachnids.
Constructing Scatterplots p. 742
How might the loss of many arachnid species affect an ecosystem?
24.3 Assessment p. 742 (1-6)

24.4: Insect Adaptations
Objectives: Contrast incomplete metamorphosis and complete metamorphosis.
            Describe how insects are adapted to life on land.
Words to Know: Incomplete Metamorphosis, Complete Metamorphosis, Pupa

Insects
    Insects have moved into virtually every ecological niches, which has helped them diversify into the
        largest group of animals.
    All insects have a body with three parts: a head, thorax, and abdomen.
    The thorax has three pairs of legs (6),and most adult insects have two pairs of wings.
    Usually have 1 pair of antennae and one pair of compound eyes.
    Many have mandibles that they use to chew up food.
    Some live in colonies of hundreds or thousands.
How are insects similar to and different from crustaceans and arachnids?
Metamorphosis
    Insects can go through two different types of metamorphosis: incomplete or complete metamorphosis.
    The pattern of development in which the immature form looks like a smaller version of the adult and go
        through a direct development is known as Incomplete Metamorphosis.
               The immature insects are often called Nymphs.
               They are the same as adults minus wings and sex organs.
      In Complete Metamorphosis, young insects do NOT look like adults but molt and change their form as
       they mature.
             Larva hatch from eggs.
             Pupa forms when the larva forms a shell called a chrysalis.
             The adult hatches .
             The mature female can lay eggs to restart the process.
24.4 Assessment p. 746 (1-6)

24.5: Arthropods and Humans
Objectives: Summarize the shared resources and interactions of arthropods and humans, including
transmission of diseases.
Words to Know: Insecticide, Vector, biomagnifications

Shared Resources
     Many insects are herbivores and eat the same plants people use for food.
     Competition is stiff because there are far more arthropods than people.
     To prevent costly infestations, farmers use insecticides to kill arthropods.
     Many insecticides are toxic to other animals, including people.
     Remember that DDT could accumulate in predator species through biomagnifications.
     Arthropods can also become resistant to toxins making them harder to kill.
     Insecticides are now being developed for specific arthropods.
     Integrated pest management reduces the number of insect pests on a plant crop by managing ecology.
     Genetically modified plants can be made that are resistant to pests.
What would be a disadvantage to introducing a predator insect for pest management?
Some Arthropods Spread Disease
     Some insects are Vectors – disease carriers.
     Bubonic Plague was carried by fleas.
              Outbreaks killed 1/3 to 1/2 of the human population, in Europe, in the 1400’s.
     Yellow Fever is caused by a virus and is carried to humans by mosquitoes.
     Malaria is caused by a protozoan parasite carried by mosquitoes.
     West Nile Virus is also carried by mosquitoes.
Explain how an organism other than an arthropod could be a vector.
24.5 Assessment p. 749 (1-5)
Daphnia and Heart Rate p. 750
Inside a Crayfish p. 751
www.classzone.com
Chapter Assessment p. 753 – 755

				
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