font settings

Font Size: Large | Normal | Small
Font Face: Verdana | Geneva | Georgia

Panarthropoda

(Superphylum)

Overview

[ Back to top ]

Panarthropoda is a 1] combining the phyla Arthropoda, Tardigrada and Onychophora.[2] Originally, they were considered to be closely related to the annelids, grouped together as the Articulata, but newer studies place them among a group called the Ecdysozoa.

Common characteristics of the Panarthropoda include the presence of legs and claws, a ventral nervous system, and a segmented body.

The term "Lobopoda" is sometimes used to describe onychophorans and tardigrades only.[3]

Photos

[ Back to top ]

Taxonomy

[ Back to top ]

The Superphylum Panarthropoda is a member of the Infrakingdom Ecdysozoa. Here is the complete "parentage" of Panarthropoda:

The Superphylum Panarthropoda is further organized into finer groupings including:

Phyla

[ Back to top ]

Arthropoda

An arthropod is an that has an exoskeleton (external skeleton), a segmented body, and jointed attachments called appendages. Arthropods are animals belonging to the Phylum Arthropoda (from Greek ?????? arthron, "joint", and p?d?? podos "foot", which together mean "jointed feet"), and include the insects, arachnids, crustaceans, and others. Arthropods are characterized by their jointed limbs and cuticles, which are mainly made of a-chitin; the cuticles of crustaceans are also biomineralized with calcium carbonate. The rigid cuticle inhibits growth, so arthropods replace it periodically by molting. The arthropod body plan consists of repeated segments, each with a pair of appendages. It is so versatile that they have been compared to Swiss Army knives, and it has enabled them to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80% of all described living species, and are one of only two animal groups that are really successful in dry environments – the other being the amniotes. They range in size from microscopic plankton up to forms a few meters long. [more]

Chordata

Chordates ( Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. They are united by having, at some time in their life cycle, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail. The phylum Chordata consists of three subphyla: Urochordata, represented by tunicates; Cephalochordata, represented by lancelets; and Craniata, which includes Vertebrata. The Hemichordata have been presented as a fourth chordate subphylum, but they are now usually treated as a separate phylum. Urochordate larvae have a notochord and a nerve cord but these are lost in adulthood. Cephalochordates have a notochord and a nerve cord but no brain or specialist sense organs, and a very simple circulatory system. Craniates are the only sub-phylum whose members have skulls. In all craniates except for Hagfish, the dorsal hollow nerve cord has been surrounded with cartilaginous or bony vertebrae and the notochord generally reduced; hence hagfish are not regarded as vertebrates. The chordates and three sister phyla, the Hemichordata, the Echinodermata and the Xenoturbellida, make up the deuterostomes, one of the two superphyla that encompass all fairly complex animals. [more]

Ciliophora

Haptophyta

The haptophytes, classed either as the Prymnesiophyta or Haptophyta, are a of algae. [more]

Onychophora

The velvet worms (Onychophora — literally "claw bearers") form a within the Ecdysozoa and can be simply described as "worms with legs". Most common in the Southern Hemisphere, they prey on smaller animals such as insects, which they catch by squirting a sticky slime. In modern zoology they are particularly renowned for their curious mating behaviour and for bearing live young. They are becoming increasingly popular in the 'exotic pets' trade, due to their bizarre appearance and eating habits. The Lobopodia, possible ancestors of velvet worms from the Cambrian period, are of great interest in paleontology. [more]

Oomycota

Oomycota also known as Water molds (or water moulds: see ) are a group of filamentous, unicellular heterokonts, physically resembling fungi. They are microscopic, absorptive organisms that reproduce both sexually and asexually and are composed of mycelia, or a tube-like vegetative body (all of an organism's mycelia are called its thallus). [more]

Tardigrada

Tardigrades (commonly known as water bears) form the Tardigrada, part of the superphylum Ecdysozoa. They are microscopic, water-dwelling, segmented animals with eight legs. Tardigrades were first described by Johann August Ephraim Goeze in 1773 (kleiner Wasserbär = little water bear). The name Tardigrada means "slow walker" and was given by Lazzaro Spallanzani in 1777. The name water bear comes from the way they walk, reminiscent of a bear's gait. The biggest adults may reach a body length of 1.5 mm, the smallest below 0.1 mm. Freshly hatched larvae may be smaller than 0.05 mm. [more]

At least 1,104 species and subspecies belong to the Phylum Tardigrada.

More info about the Phylum Tardigrada may be found here.

References

[ Back to top ]
  1. ^ Claus Nielsen (1997). Animal Evolution: Interrelationships of the Living Phyla. Oxford University Press. ISBN 0-19-850682-1. 
  2. ^ Telford MJ, Bourlat SJ, Economou A, Papillon D, Rota-Stabelli O (April 2008). "The evolution of the Ecdysozoa". Philos. Trans. R. Soc. Lond., B, Biol. Sci. 363 (1496): 1529–37. doi:10.1098/rstb.2007.2243. PMID 18192181. PMC: 2614232. http://rstb.royalsocietypublishing.org/cgi/pmidlookup?view=long&pmid=18192181. 
  3. ^ Cavalier-Smith T (August 1998). "A revised six-kingdom system of life". Biol Rev Camb Philos Soc 73 (3): 203–66. PMID 9809012. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1464-7931&date=1998&volume=73&issue=3&spage=203. 

Sources

[ Back to top ]
Last Revised: September 22, 2009
2009/09/22 05:55:00