invertebrate

/ɪnˈvʌrɾəbrət/

/ɪnˈvʌtəbrət/

Other forms: invertebrates

An invertebrate is an animal without a backbone. Invertebrate animals include fruit flies and sea sponges.

Your backbone allows you to stand up straight, and it also allows you to be grouped with the other vertebrates: animals with backbones. Invertebrates are the opposite: they have no backbone. These are the two major groups of animals. Also, this word is used for people who are spineless in the sense of having no courage. You could say a coward acts in an invertebrate way. Whether it's a backbone-free animal or a courage-free person, all invertebrates lack spines.

Definitions of invertebrate

1. noun

   any animal lacking a backbone or notochord; the term is not used as a scientific classification
   types:

   arthropod

   invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin

   zoophyte

   any of various invertebrate animals resembling a plant such as a sea anemone or coral or sponge

   parazoan, poriferan, sponge

   primitive multicellular marine animal whose porous body is supported by a fibrous skeletal framework; usually occurs in sessile colonies

   cnidarian, coelenterate

   radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms

   comb jelly, ctenophore

   biradially symmetrical hermaphroditic solitary marine animals resembling jellyfishes having for locomotion eight rows of cilia arranged like teeth in a comb

   worm

   any of numerous relatively small elongated soft-bodied animals especially of the phyla Annelida and Chaetognatha and Nematoda and Nemertea and Platyhelminthes; also many insect larvae

   borer, woodborer

   any of various insects or larvae or mollusks that bore into wood

   rotifer

   minute aquatic multicellular organisms having a ciliated wheel-like organ for feeding and locomotion; constituents of freshwater plankton

   mollusc, mollusk, shellfish

   invertebrate having a soft unsegmented body usually enclosed in a shell

   phoronid

   hermaphrodite wormlike animal living in mud of the sea bottom

   bryozoan, moss animal, polyzoan, sea mat, sea moss

   sessile aquatic animal forming mossy colonies of small polyps each having a curved or circular ridge bearing tentacles; attach to stones or seaweed and reproduce by budding

   ectoproct

   sessile mossy aquatic animal having the anus of the polyp outside the crown of tentacles

   entoproct

   any of various moss-like aquatic animals usually forming branching colonies; each polyp having a both mouth and anus within a closed ring of tentacles

   Symbion pandora

   only known species of Cycliophora; lives symbiotically attached to a lobster's lip by an adhesive disk and feeding by means of a hairy mouth ring; its complex life cycle includes asexual and sexual phases

   brachiopod, lamp shell, lampshell

   marine animal with bivalve shell having a pair of arms bearing tentacles for capturing food; found worldwide

   peanut worm, sipunculid

   small unsegmented marine worm that when disturbed retracts its anterior portion into the body giving the appearance of a peanut

   echinoderm

   marine invertebrates with tube feet and five-part radially symmetrical bodies

   trilobite

   an extinct arthropod that was abundant in Paleozoic times; had an exoskeleton divided into three parts

   arachnid, arachnoid

   an arthropod with simple eyes and four pairs of legs

   myriapod

   general term for any terrestrial arthropod having an elongated body composed of many similar segments: e.g. centipedes and millipedes

   Scutigerella immaculata, garden centipede, garden symphilid, symphilid

   minute arthropod often infesting the underground parts of truck-garden and greenhouse crops

   tardigrade, water bear

   a microscopic animal with eight legs that lives in water or moss

   centipede

   a long, venomous insect-like creature having many body segments, each with many pairs of legs and belonging in the Arthropoda phylum

   millepede, milliped, millipede

   any of numerous herbivorous nonpoisonous arthropods having a cylindrical body of 20 to 100 or more segments most with two pairs of legs

   pycnogonid, sea spider

   any of various small spiderlike marine arthropods having small thin bodies and long slender legs

   Merostomata, class Merostomata

   used in some classifications; includes the orders Xiphosura and Eurypterida

   Limulus polyphemus, Xiphosurus polyphemus, horseshoe crab, king crab

   large marine arthropod of the Atlantic coast of North America having a domed carapace that is shaped like a horseshoe and a stiff pointed tail; a living fossil related to the wood louse

   Asian horseshoe crab

   horseshoe crab of the coast of eastern Asia

   eurypterid

   large extinct scorpion-like arthropod considered related to horseshoe crabs

   pentastomid, tongue worm

   wormlike arthropod having two pairs of hooks at the sides of the mouth; parasitic in nasal sinuses of mammals

   glass sponge

   a siliceous sponge (with glassy spicules) of the class Hyalospongiae

   polyp

   one of two forms that coelenterates take (e.g. a hydra or coral): usually sedentary with a hollow cylindrical body usually with a ring of tentacles around the mouth

   medusa, medusan, medusoid

   one of two forms that coelenterates take: it is the free-swimming sexual phase in the life cycle of a coelenterate; in this phase it has a gelatinous umbrella-shaped body and tentacles

   jellyfish

   any of numerous usually marine and free-swimming coelenterates that constitute the sexually reproductive forms of hydrozoans and scyphozoans

   scyphozoan

   any of various usually free-swimming marine coelenterates having a gelatinous medusoid stage as the dominant phase of its life cycle

   hydroid, hydrozoan

   colonial coelenterates having the polyp phase dominant

   actinozoan, anthozoan

   sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed

   beroe

   delicately iridescent thimble-shaped ctenophores

   platyctenean

   ctenophore have long tentacles and flattened body

   sea gooseberry

   ctenophore having a rounded body with longitudinal rows of cilia

   Cestum veneris, Venus's girdle

   ctenophore having a ribbon-shaped iridescent gelatinous body

   helminth, parasitic worm

   worm that is parasitic on the intestines of vertebrates especially roundworms and tapeworms and flukes

   woodworm

   a larva of a woodborer

   acanthocephalan, spiny-headed worm

   any of various worms living parasitically in intestines of vertebrates having a retractile proboscis covered with many hooked spines

   arrowworm, chaetognath

   any worm of the Chaetognatha; transparent marine worm with horizontal lateral and caudal fins and a row of movable curved spines at each side of the mouth

   flatworm, platyhelminth

   parasitic or free-living worms having a flattened body

   nemertean, nemertine, proboscis worm, ribbon worm

   soft unsegmented marine worms that have a threadlike proboscis and the ability to stretch and contract

   beard worm, pogonophoran

   slender animal with tentacles and a tubelike outer covering; lives on the deep ocean bottom

   nematode, nematode worm, roundworm

   unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic

   annelid, annelid worm, segmented worm

   worms with cylindrical bodies segmented both internally and externally

   scaphopod

   burrowing marine mollusk

   gastropod, univalve

   a class of mollusks typically having a one-piece coiled shell and flattened muscular foot with a head bearing stalked eyes

   chiton, coat-of-mail shell, polyplacophore, sea cradle

   primitive elongated bilaterally symmetrical marine mollusk having a mantle covered with eight calcareous plates

   bivalve, lamellibranch, pelecypod

   marine or freshwater mollusk having a soft body with platelike gills enclosed within two shells hinged together

   cephalopod, cephalopod mollusk

   marine mollusk characterized by well-developed head and eyes and sucker-bearing tentacles

   crustacean

   any mainly aquatic arthropod usually having a segmented body and chitinous exoskeleton

   onychophoran, peripatus, velvet worm

   any of numerous velvety-skinned wormlike carnivorous animals common in tropical forests having characteristics of both arthropods and annelid worms

   insect

   a small creature with six legs, three body fragments, two antennae, and usually wings belonging in the Arthropoda phylum

   instar

   an insect or other arthropod between molts

   sea star, starfish

   echinoderms characterized by five arms extending from a central disk

   brittle star, brittle-star, serpent star

   an animal resembling a starfish with fragile whiplike arms radiating from a small central disc

   basket fish, basket star

   any starfish-like animal of the genera Euryale or Astrophyton or Gorgonocephalus having slender complexly branched interlacing arms radiating from a central disc

   sea urchin

   an echinoderm with a soft body in a thin, round, spiny, shell; usually found in shallow waters

   crinoid

   primitive echinoderms having five or more feathery arms radiating from a central disk

   holothurian, sea cucumber

   echinoderm having a flexible sausage-shaped body, tentacles surrounding the mouth and tube feet; free-living mud feeders

   type of:

   animal, animate being, beast, brute, creature, fauna

   a living organism characterized by voluntary movement
2. adjective

   lacking a backbone or spinal column
   “worms are an example of invertebrate animals”

   synonyms: spineless

   antonyms:

   vertebrate

   having a backbone or spinal column