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Onychophora (also called velvet worms, walking worms, or spitting worms) are segmented, caterpillar-like, terrestrial animals somewhat resembling both arthropods and annelid worms. They are generally regarded either as a class of arthropods or as a separate phylum (in which case they are the only animal phylum to include no marine species). About 110 modern species are known separated into two families, with 10 genera. They live in many tropical and subtropical regions worldwide including Mexico, Central America, South America, Africa, Australia and New Zealand. Modern species are fairly small; at least one species reaches lengths of 20 cm (about 8 inches). The best known modern form is Peripatus which was described by Guilding in 1825. Image File history File linksMetadata 31-Velvet_Worm. ...
Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ...
Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Myxozoa (slime animals) Superphylum Deuterostomia (blastopore becomes anus) Chordata (vertebrates, etc. ...
In biological classification, family (Latin: familia, plural familiae) is 1) a rank or 2) a taxon in that rank. ...
The striking caterpillar of the Emperor Gum Moth This article is about insect larva. ...
Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Myxozoa (slime animals) Superphylum Deuterostomia (blastopore becomes anus) Chordata (vertebrates, etc. ...
Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ...
Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata Oligochaeta - Earthworms and others Acanthobdellida Branchiobdellida Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida, are a large phylum of animals, comprising the segmented worms, with about...
Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ...
Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ...
In biology, a species is one of the basic units of biodiversity. ...
In biological classification, family (Latin: familia, plural familiae) is 1) a rank or 2) a taxon in that rank. ...
In biology, a genus (plural genera) is a taxonomic grouping. ...
The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the two tropics: the Tropic of Cancer in the north and the Tropic of Capricorn in the southern hemisphere. ...
Subtropical (or semitropical) areas are those adjacent to the tropics, usually roughly defined as the ranges 23. ...
Map of Central America Central America is a central region of the Americas. ...
South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ...
For other uses, see Africa (disambiguation). ...
Peripatus is a genus of Onychophora. ...
1825 was a common year starting on Saturday (see link for calendar). ...
Description
Onychophores are apparently descended from some segmented form but have lost their overt segmentation except for the head which is composed of three segments. There are two antennae on the first head segment and usually a pair of eyes. The second head segment has a mouth. Unlike arthropods, the animal does not have a stiff exoskeleton. Their skin (cuticle) is covered with fine hair (papillae) giving a velvet-like feel and accounting for their popular name of "velvet worms". The cuticle is shed periodically to allow growth. Although the body has several dozen repeated leg pairs, it is not actually segmented, like, say, annelids. The true coelom, like that of arthropods, is restricted almost entirely to the gonadal cavities. The hemocoel is also arthropod-like, being partitioned into sinuses, including a dorsal pericardial sinus. The entire structure is supported by blood pumped by a heart. Legs are tipped by chitinous claws and walking pads used on smooth surfaces. Onychophores breathe through passages in the skin trachea which are always open. As a result, all known species require a humid environment to avoid desiccation. Antennae (singular antenna), are the paired appendages connecting to the first (and in crustaceans also to the second) segment of the head of the members of all subphyla of the arthropods except Chelicerata. ...
In biology, cuticle or cuticula refers to a more or less tough (but flexible) non-mineral covering of an organism, or part of it. ...
A papilla (plural: papillae) can be: A small projection, such as a nipplelike projection on the skin, at the base of a hair or the root of a feather; the base of a new tooth. ...
Velvet is a type of tufted fabric in which the cut threads are very evenly distributed, with a short dense pile, giving it its distinct feel. ...
Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata Oligochaeta - Earthworms and others Acanthobdellida Branchiobdellida Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida, are a large phylum of animals, comprising the segmented worms, with about...
By the broadest definition, a body cavity is any fluid filled space in a multicellular organism. ...
An open circulatory system is an arrangement of internal transport in which blood bathes the organs directly and there is no distinction between blood and interstitial fluid. ...
Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ...
The heart and lungs, from an older edition of Greys Anatomy. ...
Structure of chitin molecule Chitin (IPA: ) is one of the main components in the cell walls of fungi, the exoskeletons of insects and other arthropods, and in some other animals. ...
Windpipe redirects here. ...
Humidity is the concentration of water vapor in the air. ...
Desiccation is the state of extreme dryness, or the process of extreme drying. ...
Behaviour Modern onychophores are predators that are able to immobilize animals several times their own size with an adhesive substance that they eject from glands in their head. They can immobilize targets up to 30 cm away, and carry a quantity of fluid of as much as 10% of their body weight. This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ...
Velvet worms have an unusual method of transferring sperm. The male onychophore attaches a sperm packet to the female. They tend to be fairly indiscriminate where on the female they attach the packet. The tissue beneath the packet dissolves and the packet melts into the female's body. The sperm swim through the hemocoel to the ovaries.
Evolution Onychophores are thought to be closely related to the arthropods. The structure of their brains is similar to spiders, raising the possibility that they are most closely related to arachnids, though molecular analysis contradicts this. Possible marine onychopores are known from the Lower Cambrian -- Aysheaia, Hallucigenia -- and possibly the late Pre-Cambrian -- Xenusion. A single fossil terrestrial species, Helenodora inopinata, is known from the Pennsylvanian of Illinois, another one by the name of Cretoperipatus burmiticus from the Cretaceous of Myanmar and some Tertiary specimens are reported from Caribbean amber. Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ...
The Cambrian is a major division of the geologic timescale that begins about 542 Ma (million years ago) at the end of the Proterozoic eon and ended about 488. ...
Aysheaia pedunculata is a soft-bodied, caterpillar-shaped organism average body length of 1-6 cm. ...
Hallucigenia is an extinct genus of animal found as fossils in the Middle Cambrian-aged Burgess Shale formation of British Columbia, Canada. ...
The Precambrian or Cryptozoic is the period of the geologic timescale from the formation of Earth around 4500 million years before the present (BP) to the evolution of abundant macroscopic hard-shelled fossils, which marked the beginning of the Cambrian, some 542 million years BP. Remarkably little is known about...
Xenusion is a possible very primitive arthropod/onychophore known from two specimens found in glacial debris in Germany. ...
The Pennsylvanian is a geologic (sub)period lasting from roughly 325 million years before the present (BP) to 286 million years BP. As with most other geologic periods, the rock beds that define the period are well identified, but the exact date of the start and end are uncertain by...
Official language(s) English Capital Springfield Largest city Chicago Area Ranked 25th - Total 57,918 sq mi (149,998 km²) - Width 210 miles (340 km) - Length 390 miles (629 km) - % water 4. ...
The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period, about 146 million years ago (Ma), to the beginning of the Paleocene epoch of the Tertiary period (65. ...
Tertiary period was previously one of the major divisions of the geologic timescale, from the end of the Cretaceous period about 65 million years ago to the start of the Quaternary period about 1. ...
Central America and the Caribbean (detailed pdf map) The Caribbean (Spanish: Caribe; French: Caraïbe; Dutch: Caraïben; Portuguese: Caribe or CaraÃbas) is a region of the Americas consisting of the Caribbean Sea, its islands (most of which enclose the sea), and the surrounding coasts. ...
Amber pendants. ...
The similarity of these creatures to caterpillars is not purely coincidental; as with most creatures, the larval stage of moths and butterflies are thought to represent, however inconsistently, previous evolutionary stages. Insects are thought to have evolved from a multi-segmented worm not entirely unlike both onychophores and caterpillars. In fact, the characteristics of larval insects are part of the evidence cited to support models of insect ancestors, for example in justifying how many segments and legs such creatures were thought to have, many of which evolved into other parts on modern insects, like antennae and mouthparts. The striking caterpillar of the Emperor Gum Moth This article is about insect larva. ...
The theory of recapitulation, also called the biogenetic law or ontogeny recapitulates phylogeny, is a theory in biology which attempts to explain apparent similarities between humans and other animals. ...
References Richard C. Brusca & Gary J. Brusca. 2003. Invertebrates. 2nd edition (January 2003), Sinauer Associates. 936 pages.
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