acorn worm

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Related to acorn worms: Hemichordata, Lancelets

acorn worm:

see HemichordataHemichordata
, small phylum of marine invertebrates closely related to both the echinoderms (phylum Echinodermata) and chordates (phylum Chordata). Acorn worms, class Enteropneusta, are the most common hemichordates.
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acorn worm

[′ā‚kȯrn ‚wərm]
(invertebrate zoology)
Any member of the class Enteropneusta, free-living animals that usually burrow in sand or mud. Also known as tongue worm.
References in periodicals archive ?
flava acorn worms also regenerate: however, their large size and opacity make them difficult to use in a variety of molecular assays.
Reproductive periodicity, spawning induction, and larval metamorphosis of the hemichordate acorn worm Ptychodera flava.
Abundance patterns of brachiopods and acorn worms in particular were similar since both groups were absent early on 1984, begun to increase and reached high numbers around the mid rainy season of 1984, became scarcer during 1985 and early 1986, and increased slightly during the dry season of 1986-1987.
The acorn worms (Enteropneusta) were represented by 16 specimens found mainly during the rainy season (Fig.
"It's astonishing how similar Spartobranchus tenuis fossils are to modern day acorn worms, except that they also formed fibrous tubes," he noted.
Researchers say these tubes were lost in the lineage that resulted in modern-day acorn worms, but were retained through graptolites and pterobranchs.
The fossils, Spartobranchus tenuis, are a member of the acorn worm group.
"There is much interest in the acorn worms from the point of view of understanding the early evolution of the vertebrates.
A reddish-purple acorn worm with large lips either side of its head region reminded researchers of floppy-eared Star Wars character Yoda while pupurata is Latin for purple and describes its colorful hue.
For histological observations, 10 infected acorn worms were anesthetized with 0.2 mol [l.sup.-1] magnesium chloride in seawater for 15 min, fixed with 4% paraformaldehyde in 0.1 mol [l.sup.-1] MOPS buffer at 4[degrees]C overnight, and then dehydrated through a graded series of ethanol concentrations.
Minuscule acorn worms may be present in samples collected elsewhere using similar methods, but may have been overlooked due to their minimal and nondescript external characters (Fig.
abundance and trail characteristics of acorn worms at Australian continental margins.