Pharynx and intestine

Tzetlin, Alexander B.; Purschke, Günter

doi:10.1007/1-4020-3240-4_12

Cited by 48 publications

(76 citation statements)

References 70 publications

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“…Annelids use a wide spectrum of food sources, and accordingly, structures involved in feeding vary greatly and show numerous specializations; in the foregut, such structures are often termed buccal organ (Purschke 1988b;Rouse 2000;Tzetlin and Purschke 2005). At least five different types of buccal organs may be distinguished in annelids, one of which is commonly called ventral pharynx (Tzetlin and Purschke 2005).…”

Section: Ventral Pharynxmentioning

confidence: 99%

“…At least five different types of buccal organs may be distinguished in annelids, one of which is commonly called ventral pharynx (Tzetlin and Purschke 2005). Ventral pharyngeal organs usually are epithelial and muscular structures lying beneath the oesophagus, divided by a few blind-ending pouches.…”

Section: Ventral Pharynxmentioning

confidence: 99%

“…Above this bulb, a so-called tongue-like organ may be present. These parts are ventrally enveloped and connected by a longitudinal muscle, the investing muscle (Purschke 1988b;Tzetlin and Purschke 2005). Such ventral pharynges are widespread among polychaetes.…”

Section: Ventral Pharynxmentioning

confidence: 99%

“…One of these characters, which might have some importance to support this grouping is the ventral pharynx (Giere and Riser 1981), which as such, however, is widespread among unrelated polychaetes (Purschke 1988b;Tzetlin and Purschke 2005). Usually members of Orbiniidae possess an axial pharynx.…”

Section: Introductionmentioning

confidence: 99%

“…In juveniles, this pharynx is replaced when animals grow and development proceeds. Since such ventral pharynges show specific substructures (Tzetlin and Purschke 2005), an ultrastructural analysis of this organ in Questa paucibranchiata was carried out to look for potential apomorphic characters shared with other orbiniids and to elucidate their evolutionary history.…”

Section: Introductionmentioning

confidence: 99%

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Ultrastructure of the ventral pharynx in the interstitial annelid Questa paucibranchiata (Orbiniidae) and its phylogenetic significance

2011

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The small taxon Questa comprises only meiofaunal species and shows oligochaete-like adaptations in its reproductive biology. Formerly, it was classified as a separate polychaete group, Questidae, of uncertain affinities, but due to these oligochaete-like similarities, a relationship with Clitellata was discussed. However, other morphological phylogenetic analyses questioned such a relationship, providing evidence for common ancestry with Paraonidae and Orbiniidae. Molecular studies revealed that questids even form an in-group of Orbiniidae, which refutes a clitellate relationship without doubt. On the other hand, morphological evidence supporting this grouping is still considered weak. Among the external characters, the chaetation, comprising crenulated capillaries, hooks and furcate chaetae, might strengthen this hypothesis. One of the internal characters stated to support this grouping is the ventral pharynx, which as such, however, is widespread among polychaetes. This study is a first attempt to look for specific structures in this organ, which might be regarded as synapomorphic of Questa and Orbiniidae. The ultrastructural analysis revealed a ventral buccal organ composed of large interstitial cells and transverse muscle fibres and surrounded by an investing muscle system similar to that found in juvenile Orbiniidae. Thus, further morphological evidence for the current position is provided. Moreover, since this structure is known as a larval or juvenile character in Orbiniidae, this finding is also indicative for a progenetic origin of Questa, which might have occurred upon invading the interstitial environment.

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Section: Ventral Pharynxmentioning

confidence: 99%

Section: Ventral Pharynxmentioning

confidence: 99%

Section: Ventral Pharynxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrastructure of the ventral pharynx in the interstitial annelid Questa paucibranchiata (Orbiniidae) and its phylogenetic significance

2011

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Hooking some stem‐group “worms”: fossil lophotrochozoans in the Burgess Shale

Butterfield

2006

BioEssays

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The fossil record plays a key role in reconstructing deep evolutionary relationships through its documentation of the early diverging stem groups leading to extant phyla. In the middle Cambrian Burgess Shale, two famously problematic worms, Odontogriphus and Wiwaxia, have recently been reinterpreted as stem-group molluscs based on their shared expression of a putative radula and putative ctenidia in Odontogriphus. More detailed analysis of these fossil structures, however, reveals pronounced anatomical and histological discrepancies with molluscan analogues, such that they are more reliably interpreted as primitive features of the superphylum Lophotrochozoa. In the absence of any obviously derived characters, Odontogriphus could be placed in the stem group of the Lophotrochozoa or on the stem of any of its constituent phyla, whereas the dorsal covering of chaetae in Wiwaxia identifies it as a stem-group polychaete. Despite their close relationship, these two jawed, segmented worms could conceivably represent the early stages of two separate phyla.

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Jaw morphology and ontogeny in five species of Ophryotrocha

Macnaughton

Worsaae

Eibye‐Jacobsen

2009

Journal of Morphology

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Detailed scanning electron microscopy of jaws within the genus Ophryotrocha (Dorvilleidae, Annelida) was performed on 871 jaw parts. The investigations resulted in new understandings of the ontogeny and jaw morphology and have systematic implications for the family. Five species in the genus (Ophryotrocha alborana, O. diadema, O. gracilis, O. hartmanni, and O. labronica pacifica) were kept in culture, and the development of the jaws was studied by sampling throughout their life history. Ophryotrocha species have mandibular plates that remain the same throughout ontogeny, whereas the posterior shafts elongate. Both mandibular plate morphology and shaft ontogeny have species-specific distinctions. In Ophryotrocha, the maxillae can be assigned to three to four distinct types, which are replaced by moulting. The maxillary morphology and developmental stages at which moults occur are species specific, although with broad intervals. A redefinition is given for some of the basic jaw elements, and new homologies are proposed for structures that are also present across other dorvilleid taxa.

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Pharynx and intestine

Cited by 48 publications

References 70 publications

Ultrastructure of the ventral pharynx in the interstitial annelid Questa paucibranchiata (Orbiniidae) and its phylogenetic significance

Ultrastructure of the ventral pharynx in the interstitial annelid Questa paucibranchiata (Orbiniidae) and its phylogenetic significance

Hooking some stem‐group “worms”: fossil lophotrochozoans in the Burgess Shale

Jaw morphology and ontogeny in five species of Ophryotrocha

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