''Ottoia'' is a stem-group archaeopriapulid worm known from

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

fossils. Although priapulid-like worms from various Cambrian deposits are often referred to ''Ottoia'' on spurious grounds, the only clear ''Ottoia'' macrofossils come from the

Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest foss ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

, which was deposited . Microfossils extend the record of ''Ottoia'' throughout the

Western Canada Sedimentary Basin The Western Canadian Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary ...

, from the mid- to late- Cambrian. A few fossil finds are also known from China.

Morphology

''Ottoia'' specimens are on average 8 centimeters in length. Both length and width show variation with contraction; shorter specimens often being wider than longer ones. The characteristic

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

of priapulids is present at the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

, attached to the trunk of the animal, proceeded by the "bursa" at the posterior. The organism's body is bilaterally symmetrical, however, its anterior displays external radial symmetry. Like some other modern invertebrates, a

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

restricts the size of and protects the animal. The trunk hosts the internal organs of the organism, divided into seventy to a hundred annulations of varying spacing, depending on curvature and contraction. The posterior displays a series of hooks, which likely acted as anchors during burrowing. Muscles support the animal and retract the bursa and proboscis. A gut leading from the anus in the bursa to the mouth in the proboscis runs through the trunk's spacious body cavity, and a concentration of gut muscles serve the function of a

gizzard The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, dinosaurs, birds), earthworms, some gastropods, so ...

. A nerve chord runs down the organism's length. In addition to the other organs, it is possible ''Ottoia'' contained urogenital organs in its trunk. There is no evidence of a respiratory organ, though the bursa may have served this purpose. Ottoia sclerites - schematic

The everted proboscis of ''Ottoia'' bears an armature of teeth and hooks. The detailed morphology of these elements distinguishes the two described species, ''O. tricuspida'' and ''O. prolifica''. At the base of the pharynx, separated from the teeth by an unarmed region, sits a ring of spines. Behind this, at the front of the trunk, lies a series of hooks and spines, arranged in a quincunx pattern like the five dots on a

domino Dominoes is a family of tile-based games played with gaming pieces, commonly known as dominoes. Each domino is a rectangular tile, usually with a line dividing its face into two square ''ends''. Each end is marked with a number of spots (also ca ...

die Die, as a verb, refers to death, the cessation of life. Die may also refer to: Games * Die, singular of dice, small throwable objects used for producing random numbers Manufacturing * Die (integrated circuit), a rectangular piece of a semicondu ...

Ecology

''Ottoia'' was a burrower that hunted prey with its eversible proboscis. It also appears to have scavenged on dead organisms such as the arthropod ''

Sidneyia ''Sidneyia'' is an extinct arthropod known from fossils found from the Early Cambrian-age Maotianshan Shales to the Mid Cambrian Burgess Shale formation of British Columbia. 144 specimens of ''Sidneyia'' are known from the Greater Phyllopod bed, ...

''. The spines on the proboscis of ''Ottoia'' have been interpreted as teeth used to capture prey. Its mode of life is uncertain, but it is thought to have been an active burrower, moving through the sediment after prey, and is believed to have lived within a U-shaped burrow that it constructed in the substrate. From that place of relative safety, it could extend its proboscis in search of prey. Gut contents show that this worm was a

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

, often feasting on the

hyolithid Hyoliths are animals with small conical shells, known as fossils from the Palaeozoic era. They are at least considered as lophotrochozoan, and possibly being lophophorates, a group which includes the brachiopods, while others consider them as be ...

''Haplophrentis'' (a shelled animal similar to mollusks), generally swallowed them head-first. They also show evidence of

cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, b ...

, which is common in priapulids today.

Preservation

Because of its bottom-living habit and the location of the Burgess Shale site at the foot of a high limestone reef, one may presume the relative immobility of ''Ottoia'' placed it in danger of being carried away and/or buried by any underwater mud avalanche from the cliff top. This may explain why it remains one of the more abundant specimens of the Burgess Shale fauna.

Distribution

At least 1000 Burgess Shale specimens are known in the UNSM collections alone, in addition to the ROM collections and hundreds of specimens elsewhere. 677 specimens of ''Ottoia'' are known from the Greater

Phyllopod bed The Phyllopod bed, designated by USNM locality number 35k, is the most famous fossil-bearing member of the Burgess Shale fossil ''Lagerstätte''. It was quarried by Charles Walcott from 1911–1917 (and later named Walcott Quarry), and was t ...

, where they comprise 1.29% of the community. ''Ottoia'' has also been reported from Middle Cambrian deposits in Utah and Spain, Nevada, and various other localities. Nevertheless, these reports are insecure, and the only verifiable ''Ottoia'' macrofossils herald from the Burgess Shale itself. Microfossils corresponding to ''Ottoia'' teeth, however, have a much broader distribution, and are found throughout the Western Canada Sedimentary Basin. Indeed, putative candidates (initially described under the ICBN as ''Goniomorpha'') may extend the range of ''Ottoia'', or at least similar priapulans, into the Ordovician.

References

External links

*
''Ottoia prolifica'' (A priapulid worm) from the Smithsonian Institution.
{{Taxonbar, from1=Q20672214, from2=Q1953019 Prehistoric protostome genera Burgess Shale fossils Cambrian invertebrates Priapulida Miaolingian first appearances Furongian extinctions Fossil taxa described in 1911 Wheeler Shale Cambrian genus extinctions