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Canadia (genus)
Encyclopedia
Canadia is a genus of extinct annelid worm present in Burgess Shale type Konservat-Lagerstätte
. It is found in strata dating back to the Delamaran stage of the Middle Cambrian
around 505 million years ago, during the time of the Cambrian explosion
. It was about 3 centimeters (1.18 in) in length. Charles Doolittle Walcott
named Canadia in 1911 after Canada
, the country from which its remains have been found.
e extending from dorsal branches of notopodia) along the back of the animal that are characteristic of polychaete
worms. It has been suggested that these notosetae may have been iridescent when the organism was alive due to evidence of diffraction grating
s found on the surface of some fossils. . Tentacle
s extended from the prostomium
and may have served as sensory organs. The gut of Canadia was straight and had the ability to extend out of the body in the form of a proboscis
, suggesting that the animal was carnivorous. This is further evidenced by the lack of sediments found in the gut that would be present in a benthic detritivore
. Canadia is thought to have swum above the seafloor as a primary means of locomotion by beating its numerous notosetae. It also had the ability to travel along the seafloor using its legs. Canadia grew to 2-8 inches (5-20 centimeters) long.
along with Wiwaxia
, another organism from the Burgess Shale. Both were placed in a new superfamily called Canadiacea, and were thought to be of closer relationship to each other than to modern annelids. However, Wiwaxia
is no longer believed to have been an annelid and there is currently dispute as to whether or not Canadia should be classified as belonging to anything more derived than Polychaeta.
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
. It is found in strata dating back to the Delamaran stage of the Middle Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
around 505 million years ago, during the time of the Cambrian explosion
Cambrian explosion
The Cambrian explosion or Cambrian radiation was the relatively rapid appearance, around , of most major phyla, as demonstrated in the fossil record, accompanied by major diversification of other organisms, including animals, phytoplankton, and calcimicrobes...
. It was about 3 centimeters (1.18 in) in length. Charles Doolittle Walcott
Charles Doolittle Walcott
Charles Doolittle Walcott was an American invertebrate paleontologist. He became known for his discovery in 1909 of well-preserved fossils in the Burgess Shale of British Columbia, Canada.-Early life:...
named Canadia in 1911 after Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, the country from which its remains have been found.
Description
The most notable feature of Canadia is the many notosetae (rigid setaSeta
Seta is a biological term derived from the Latin word for "bristle". It refers to a number of different bristle- or hair-like structures on living organisms.-Animal setae:In zoology, most "setae" occur in invertebrates....
e extending from dorsal branches of notopodia) along the back of the animal that are characteristic of polychaete
Polychaete
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...
worms. It has been suggested that these notosetae may have been iridescent when the organism was alive due to evidence of diffraction grating
Diffraction grating
In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as...
s found on the surface of some fossils. . Tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s extended from the prostomium
Prostomium
Prostomium is the first body segment in annelid worms. It is in front of the mouth, being usually a small shelf- or lip-like extension over the dorsal side of the mouth. It sometimes bears antennae and eyes. It often functions like a kind of overlip when the animal is feeding...
and may have served as sensory organs. The gut of Canadia was straight and had the ability to extend out of the body in the form of a proboscis
Proboscis
A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In simpler terms, a proboscis is the straw-like mouth found in several varieties of species.-Etymology:...
, suggesting that the animal was carnivorous. This is further evidenced by the lack of sediments found in the gut that would be present in a benthic detritivore
Detritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...
. Canadia is thought to have swum above the seafloor as a primary means of locomotion by beating its numerous notosetae. It also had the ability to travel along the seafloor using its legs. Canadia grew to 2-8 inches (5-20 centimeters) long.
Classification
There has been some debate as to the placement of Canadia within the Annelida phylum. Although it is commonly accepted to be within Annelida, it is uncertain of how it relates to modern annelids. Most paleontologists agree that it belongs to the class Polychaeta due in part to the presence of Parapodium. It has been proposed to be a member of the order PhyllodocidaPhyllodocida
Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine though some are found in brackish water. Most are active benthic creatures, moving over the surface or burrowing in sediments, or living in cracks and crevices in bedrock. A few construct tubes in...
along with Wiwaxia
Wiwaxia
Wiwaxia is a genus of soft-bodied, scale-covered animals known from Burgess shale type Lagerstätte dating from the upper Lower Cambrian to Middle Cambrian. The organisms are mainly known from dispersed sclerites; articulated specimens, where found, range from to a little over 50.8 millimeters in...
, another organism from the Burgess Shale. Both were placed in a new superfamily called Canadiacea, and were thought to be of closer relationship to each other than to modern annelids. However, Wiwaxia
Wiwaxia
Wiwaxia is a genus of soft-bodied, scale-covered animals known from Burgess shale type Lagerstätte dating from the upper Lower Cambrian to Middle Cambrian. The organisms are mainly known from dispersed sclerites; articulated specimens, where found, range from to a little over 50.8 millimeters in...
is no longer believed to have been an annelid and there is currently dispute as to whether or not Canadia should be classified as belonging to anything more derived than Polychaeta.