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OverviewAI-generated
Echiura is a subclass within the class Polychaeta of the phylum Annelida. The taxon was described by Sedgwick in 1898 and is currently accepted as a valid classification. Common names for these organisms include echiuroid worms and skjeormer. They inhabit both marine and brackish environments.
Records for Echiura are held by institutions including CAS, ALMNH, CMN, UAM, and FMNH. These records document occurrences in the United States, Philippines, Mexico, Papua New Guinea, and Thailand. The taxon has been described in the Encyclopædia Britannica 11th edition.
Synthesized by Vinony from 21 facts across 4 sources: Wikidata, iDigBio, WoRMS, Vinony graph. Generated from structured data (not the Wikipedia text) and checked against those facts — may still contain errors.
Species
echiuroid worms
Subclass
- PhylumAnnelida
- ClassPolychaeta
螠虫目（学名：Echiuroidea），亦作螠目，舊作螠虫动物門或螠虫动物綱（Echiura），是动物界环节动物门的一类生活中海洋中的底栖动物。主要生活在浅海的泥沙中、岩石缝中以及珊瑚礁或贝壳中穴居，也有在深海生活的物種。 原來是一個綱，但支序分類學的研究發現其應該放在多毛綱之下，只是在進化過程中其體節消失了。 現時是多毛綱下的一個亞綱，只有螠虫目一個目，已描述的物種超過230種。 身体被隔膜分为口前叶和躯干两部分。躯干袋状，通常比口前叶短。由封闭的血管系统，但其中不含呼吸色素。躯干的肌肉分8层，环形，纵形和斜肌。体内有很长的肠道，有副肠，开口于共泄腔。有一个或两个后肾，在躯干前部。通过肛管排泄。雌雄异体。咽环，腹丛，以及由此环形分枝到背部的神经组成其神经系统。 雄性体型极小，生活在雌性身上。雄性会把精子排到雌性的肾管中。受精后的形成的幼虫生活在水中。其性别通过环境刺激决定。 這個分類的物種很難被化石化，其現存最早的化石紀錄只去到上石炭世；但牠們生活的棲管卻在沉積層中被保留下來。在寒武紀的沉積層有發現U形的棲管化石，這些棲管化石很可能是由螠蟲留下的。
via
Museum specimens
- Specimen records
- 50
- With media
- 8
- Family
- Echiuridae
- Collections
- CAS, ALMNH, CMN, UAM, FMNH, UF
- Recorded in
- United States, Philippines, Mexico, Papua New Guinea, Thailand, Antarctica, Canada, Mariana Islands
~13 min read
Encyclopedic overview
9 sectionsContents
- Taxonomy and evolution
- Anatomy
- Distribution and habitat
- Behaviour
- Reproduction
- Culinary use
- List of families
- References
- External links
thumb|right|120px|Echiurus
The Echiura, or spoon worms, are a small group of marine animals. Once treated as a separate phylum, they are now considered to belong to Annelida. Annelids typically have their bodies divided into segments, but echiurans have secondarily lost their segmentation. The majority of echiurans live in burrows in soft sediment in shallow water, but some live in rock crevices or under boulders, and there are also deep sea forms. More than 230 species have been described. Spoon worms are cylindrical, soft-bodied animals usually possessing a non-retractable proboscis which can be rolled into a scoop-shape to feed. In some species the proboscis is ribbon-like, longer than the trunk and may have a forked tip. Spoon worms vary in size from less than a centimetre in length to more than a metre.
Excerpted from Wikipedia’s “Echiura” article, available under the CC BY-SA 4.0 licence.