is an animal
without a skeletal
structure. The group
includes 95% of all animal species
animals except those in the Chordate
, and mammals
' Systema Naturae
divided these animals
into only two groups, the Insecta
). Jean-Baptiste Lamarck, who was
appointed to the position of "Curator of Insecta and Vermes" at the
Muséum National d'Histoire
Naturelle in 1793, both coined the term "invertebrate" to
describe such and divided the original two groups into ten, by
splitting off Arachnida and Crustacea from the Linnean Insecta, and Mollusca, Annelida,
Cirripedia, Radiata, Coelenterata
and Infusoria from the Linnean
They are now classified into over 30 phyla
, from simple organisms such as
to complex animals such as arthropods
Invertebrates form a paraphyletic
group. (For a full list of animals considered to be invertebrates,
.) All the listed phyla are
invertebrates along with two of the three subphyla
in Phylum Chordata
. These two, plus all the
other known invertebrates, have only one cluster of Hox genes
, while the vertebrates have duplicated
their original cluster more than once.
, invertebrates big and small are
often studied within the fossil
Phyla and common examples
- Arthropoda — insects, arachnids, crustaceans
- Nematoda — round
- Mollusca — squid,
- Annelida — segmented worms (earthworms, leeches, polychaetes)
- Nemertea — ribbon worms
- Platyhelminthes — flat worms
- Ctenophora — Comb jellies
- Cnidaria — jellyfishes, corals, sea anemones, hydras
- Porifera — sponges
- Echinoderms - starfishes, sea
- Encarta Reference
Library Home Premium 2005 DVD. Article - Invertebrate.
- Hyman, L. H. 1940. The Invertebrates (6 volumes)
New York : McGraw-Hill. A classic work.
- Anderson, D. T. (Ed.). (2001). Invertebrate zoology
(2nd ed.). Oxford: Oxford University Press.
- Brusca, R. C., & Brusca, G. J. (2003).
Invertebrates (2nd ed.). Sunderland, Mass. : Sinauer
- Miller, S.A., & Harley, J.P. (1996). Zoology (4th
ed.). Boston: WCB/McGraw-Hill.
- Ruppert, E. E., Fox, R. S., & Barnes, R. D. (2004).
Invertebrate zoology: a functional evolutionary approach.
Belmont, CA: Thomas-Brooks/Cole.