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INVERTEBRATE - Coggle Diagram

- - - - Amoebocytes are found in the mesohyl and play roles in digestion and structure
- - - - A single opening functions as mouth and anus
      - They exhibit a relatively simple diploblastic, radial body plan
      - Cnidarians have diversified into a wide range of both sessile and motile forms including jellies, corals, and hydras
      - BODY PLAN
        
        the sessile polyp
        
        A polyp adheres to the substrate by the aboral end of its body
        
        motile medusa
        
        A medusa has a bell-shaped body with its mouth on the underside
        
        Medusae do not attach to the substate but move freely
    - - The tentacles are armed with cnidocytes, unique cells that function in defense and capture of prey
      - Nematocysts are specialized organelles within cnidocytes that eject a stinging thread
    - - – Scyphozoa (jellies)
        
        In the class Scyphozoa, jellies (medusae) are the prevalent form of the life cycle
      - – Cubozoa (box jellies)
        
        In the class Cubozoa, which includes box jellies and sea wasps, the medusa is box-shaped and has complex eyes
        
        Cubozoans often have highly toxic cnidocytes
        Chironex fleckeri
      - HYDROZOANS
        
        Most hydrozoans alternate between polyp and medusa forms
        
        Hydra, a freshwater cnidarian, exists only in polyp form and reproduces asexually by budding
      - – Anthozoa (sea anemone, coral
        
        Corals often form symbioses with algae and secrete a hard external skeleton
        
        Class Anthozoa includes the corals and sea anemones, and these cnidarians occur only as polyps
  - - - CHARACTERISTICS
        
        covered by a tough coat called a cuticle
        
        The cuticle is shed or molted through a process called ecdysis
      - PHYLA
        
        NEMATODES
        
        Nematodes, or roundworms, are found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals
        
        They have an alimentary canal, but lack a circulatory system
        
        Reproduction in nematodes is usually sexual, by internal fertilization
        
        Caenorhabditis elegans is a model organism in research
        
        Some species of nematodes are important parasites of plants and animals
        
        Thrichinella spiralis can be acquired by humans from undercooked pork
        
        ARTHROPODS
        
        Two out of every three known species of animals are arthropods
        
        Members of the phylum Arthropoda are found in nearly all habitats of the biosphere
        
        ORIGIN
        
        BODY PLAN
        
        segmented body
        
        hard exoskeleton
        
        jointed appendages
        
        This body plan dates to the Cambrian explosion (535–525 million years ago)
        
        Early arthropods show little variation from segment to segment
        
        Arthropod evolution is characterized by a decrease in the number of segments and an increase in appendage specialization
        
        These changes may have been caused by changes in Hox gene sequence or regulation
        
        CHARACTERISTICS
        
        The appendages of some living arthropods are modified for functions such as walking, feeding, sensory reception, reproduction, and defense
        
        The body of an arthropod is completely covered by the cuticle, an exoskeleton made of layers of protein and the polysaccharide chitin
        
        When an arthropod grows, it molts its exoskeleton
        
        Arthropods have eyes, olfactory receptors, and antennae that function in touch and smell
        
        Arthropods have an open circulatory system in which segmented body, hard exoskeleton, and jointed appendages is circulated into the spaces surrounding the tissues and organs
        
        A variety of organs specialized for gas exchange have evolved in arthropods
        
        MAJOR LINEAGES
        
        Chelicerates (sea spiders, horseshoe crabs, scorpions, ticks, mites, and spiders)
        
        Chelicerates, subphylum Chelicerata, are named for clawlike feeding appendages called chelicerae
        
        The earliest cheliceriforms were eurypterids (water scorpions)
        
        Most marine cheliceriforms (including eurypterids) are extinct, but some species survive today, including horseshoe crabs
        
        Most modern cheliceriforms are arachnids, which include spiders, scorpions, ticks, and mites
        
        Arachnids have an abdomen and a cephalothorax, which has six pairs of appendages: the chelicerae, the pedipalps, and four pairs of walking legs
        
        Gas exchange in spiders occurs in respiratory organs called book lungs
        
        Many spiders produce silk, a liquid protein, from specialized abdominal glands
        
        Myriapods (centipedes and millipedes)
        
        Subphylum Myriapoda includes millipedes and centipedes
        
        Myriapods are terrestrial, and have jaw-like mandibles
        
        Millipedes eat decaying leaves and plant matter
        
        Millipedes have many legs, with two pairs per trunk segment
        
        CENTIPEDES
        
        carnivores
        
        have one pair of legs per trunk segment
        
        Hexapods (insects and relatives)
        
        Subphylum Hexapoda, insects and relatives, has more species than all other forms of life combined
        
        They live in almost every terrestrial habitat and in fresh water
        
        The internal anatomy of an insect includes several complex organ systems
        
        Insects diversified several times following the evolution of flight, adaptation to feeding on gymnosperms, and the expansion of angiosperms
        
        Insect and plant diversity declined during the Cretaceous extinction, but has been increasing in the 65 million years since
        
        Flight is one key to the great success of insects
        
        An animal that can fly can escape predators, find food, and disperse to new habitats much faster than organisms that can only crawl
        
        Many insects undergo metamorphosis during their development
        
        In incomplete metamorphosis, the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size
        
        Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar
        
        The larval stage looks entirely different from the adult stage
        
        Most insects have separate males and females and reproduce sexually
        
        Individuals find and recognize members of their own species by bright colors, sound, or odors
        
        Some insects are beneficial as pollinators, while others are harmful as carriers of diseases, or pests of crops
        
        Insects are classified into more than 30 orders
        
        Crustaceans (crabs, lobsters, shrimps, barnacles, and many others)
        
        While arachnids and insects thrive on land, crustaceans, for the most part, have remained in marine and freshwater environments
        
        Crustaceans, subphylum Crustacea, typically have branched appendages that are extensively specialized for feeding and locomotion
        
        Small crustaceans exchange gases through the cuticle; larger crustaceans have gills
        
        Most crustaceans have separate males and females
        
        Isopods include terrestrial, freshwater, and marine species
        
        Pill bugs are a well known group of terrestrial isopods
        
        Decapods are all relatively large crustaceans and include lobsters, crabs, crayfish, and shrimp
        
        Planktonic crustaceans include many species of copepods
        
        BARNICLE
        
        Barnacles are a group of mostly sessile crustaceans
        
        They have a cuticle that is hardened into a shell
    - - Chordates (phylum Chordata) include the vertebrates
        
        Phylum Chordata consists of two subphyla of invertebrates as well as hagfishes and vertebrates
        
        Chordates are bilaterally symmetrical coelomates with segmented bodies
        
        Chordates share many features of embryonic development with echinoderms, but have evolved separately for at least 500 million years
      - Echinoderms (phylum Echinodermata) include sea stars and sea urchins
        
        Sea stars and most other echinoderms are slow-moving or sessile marine animals
        
        A thin epidermis covers an endoskeleton of hard calcareous plates
        
        Echinoderms have a unique water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion and feeding
        
        Males and females are usually separate, and sexual reproduction is external
        
        Most adult echinoderms have radial symmetry with multiples of five
        
        Echinoderm larvae have bilateral symmetry
        
        CLASSES
        
        Asteroidea (sea stars and sea daisies)
        
        Sea stars have multiple arms radiating from a central disk
        
        The undersurface of each arm bears tube feet, which grip substrate with adhesive chemicals
        
        Sea stars feed on bivalves by prying them open with their tube feet, everting their stomach, and digesting their prey externally with digestive enzymes
        
        Sea stars can regrow lost arms
        
        Sea daisies were discovered in 1986, and only three species are known
        
        Sea daisies live on submerged wood and absorb nutrients through a membrane that surrounds their body
        
        Ophiuroidea (brittle stars)
        
        Brittle stars have a distinct central disk and long, flexible arms, which they use for movement
        
        Some species are suspension feeders, while others are predators or scavengers
        
        Echinoidea (sea urchins and sand dollars)
        
        Sea urchins and sand dollars have no arms but have five rows of tube feet
        
        Their spines are used for locomotion and protection
        
        Sea urchins feed on seaweed using a jaw-like structure on their underside
        
        Crinoidea (sea lilies and feather stars)
        
        Sea lilies live attached to the substrate by a stalk
        
        Feather stars can crawl using long, flexible arms
        
        Both are suspension feeders
        
        Holothuroidea (sea cucumbers)
        
        Sea cucumbers lack spines, have a very reduced endoskeleton, and do not look much like other echinoderms
        
        Sea cucumbers have five rows of tube feet; some of these are developed as feeding tentacles
      - share developmental characteristics
        
        Radial cleavage
        
        Formation of the anus from the blastopore
        
        defined primarily by DNA similarities
    - - CHARACTERISTICS
        
        Some develop a lophophore for feeding, others pass through a trochophore larval stage, and a few have neither feature
        
        Most have a coelom and a digestive tract with two openings
      - a clade identified by molecular data, have the widest range of animal body forms
      - Lopho=crested, trocho=wheel-like -zoa=organism
      - EG:
        
        FLATWORMS
        
        They are flattened dorsoventrally and have a gastrovascular cavity with one opening
        
        Although flatworms undergo triploblastic development, they are acoelomates
        
        Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats
        
        (phylum Platyhelminthes
        
        Gas exchange takes place across the surface, and protonephridia regulate the osmotic balance
        
        LINEAGES
        
        Catenulida, or “chain worms,” reproduce asexually by budding
        
        Rhabditophora are more diverse and include both free-living and parasitic species
        
        PLANARIAN
        
        Planarians live in fresh water and prey on smaller animals
        
        Planarians have light-sensitive eyespots and centralized nerve nets
        
        The planarian nervous system is more complex and centralized than the nerve nets of cnidarians
        
        Planarians are hermaphrodites and can reproduce sexually, or asexually through fission
        
        PARASITIC
        
        TREMADOTES
        
        3 more items...
        
        TAPEWORMS
        
        5 more items...
      - ROTIFERS
        
        Rotifers are smaller than many protists but are truly multicellular and have specialized organ systems
        
        Rotifers, phylum Rotifera, are tiny animals that inhabit fresh water, the ocean, and damp soil
        
        Rotifers have an alimentary canal, a digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom
        
        Rotifers reproduce by parthenogenesis, in which females produce offspring from unfertilized eggs
        
        Some species are unusual in that they lack males entirely
      - LOPHOPHORATES
        
        Lophophorates have a true coelom
        
        Lophophorates have a lophophore, a crown of ciliated tentacles around their mouth
        
        Lophophorates include two phyla: Ectoprocta and Brachiopoda
        
        PHYLUM
        
        ECTOPROCTS
        
        (also called bryozoans) are sessile colonial animals that superficially resemble plants
        
        A hard exoskeleton encases the colony, and some species are reef builders
        
        BRACHIOPODS
        
        superficially resemble clams and other hinge-shelled molluscs, but the two halves of the shell are dorsal and ventral rather than lateral as in clams
        
        Brachiopods are marine and attach to the seafloor by a stalk
      - MOLLUSCS
        
        Most molluscs are marine, though some inhabit fresh water and some snails and slugs are terrestrial
        
        Molluscs are soft-bodied animals, but most are protected by a hard shell
        
        snails and slugs, oysters and clams, and octopuses and squids
        
        BODY PLAN
        
        Muscular foot
        
        Visceral mass
        
        Mantle
        
        Many molluscs also have a water-filled mantle cavity and feed using a rasplike radula
        
        have separate sexes with gonads located in the visceral mass, but many snails are hermaphrodites
        
        The life cycle of many molluscs includes a ciliated larval stage called a trochophore
        
        MAJOR CLASSES
        
        Polyplacophora (chitons)
        
        Chitons are oval-shaped marine animals encased in an armor of eight dorsal plates
        
        They use their foot like a suction cup to grip rock, and their radula to scrape algae off the rock surface
        
        Gastropoda (snails and slugs)
        
        About three-quarters of all living species of molluscs are gastropods
        
        Most gastropods are marine, but many are freshwater and terrestrial species
        
        The most distinctive characteristic of gastropods is torsion, which causes the animal’s anus and mantle to end up above its head; torsion is different from the coiling of a shell
        
        Most have a single, spiraled shell
        
        Slugs lack a shell or have a reduced shell
        
        Bivalvia (clams, oysters, and other bivalves)
        
        Bivalves are marine and include many species of clams, oysters, mussels, and scallops
        
        They have a shell divided into two halves drawn together by adductor muscles
        
        Some bivalves have eyes and sensory tentacles along the edge of their mantle
        
        The mantle cavity of a bivalve contains gills that are used for feeding as well as gas exchange
        
        Cephalopoda
        
        (squids, octopuses, cuttlefish, and chambered nautiluses)
        
        Cephalopods are carnivores with beak-like jaws surrounded by tentacles of their modified foot
        
        Most octopuses creep along the sea floor in search of prey
        
        Squids use their siphon to fire a jet of water, which allows them to swim very quickly
        
        One small group of shelled cephalopods, the nautiluses, survives today
        
        Cephalopods have a closed circulatory system, well-developed sense organs, and a complex brain
        
        Shelled cephalopods called ammonites were common but went extinct at the end of the Cretaceous 65.5 million years ago
        
        The most threatened groups
        
        Freshwater bivalves, including pearl mussels
        
        Terrestrial gastropods, including Pacific island land snails
      - ANNELIDS
        
        bodies composed of a series of fused rings
        
        coelomates
        
        PHYLUM
        
        Polychaeta (polychaetes)
        
        Members of class Polychaetes have paddle-like parapodia that work as gills and aid in locomotion
        
        Most polychaetes are marine
        
        Oligochaeta (earthworms and their relatives, and leeches)
        
        Oligochaetes (class Oligochaeta) are named for relatively sparse chaetae, bristles made of chitin
        
        EARTHWORMS
        
        Earthworms eat through soil, extracting nutrients as the soil moves through the alimentary canal
        
        Earthworms are hermaphrodites but cross-fertilize
        
        Some reproduce asexually by fragmentation
        
        LEECHES
        
        Most species of leeches live in fresh water; some are marine or terrestrial
        
        Leeches include predators of invertebrates, and parasites that suck blood
        
        Leeches secrete a chemical called hirudin to prevent blood from coagulating