223
teeth per row. Within the group, the tooth morphology is extremely variable, some
having strongly elongated marginal teeth (e.g. Marshall 1978; Nützel 1998). It is
obvious that this represents an adaptation to the feeding on sponges but feeding
mechanisms have not been studied.
Cerithiopsidae sensu strictu are at least as old as Danian and are richly diversified
in the Danian Naesekalk from Denmark (Ravn 1933; Nützel 1998; Wesenberg and
Schnetler 2014) (Fig. 6.5f). The higher category Triphoroidea (respectively
Cerithiopsoidea) is older with a good fossil record from the Cretaceous and some
Jurassic representatives with the earliest record from the Bathonian (Nützel 1998
and references therein). The Triassic Protorculidae (earliest record Early Triassic,
Smithian) probably represent its fossil sister group (Nützel 1998; Nützel and
Erwin 2002).
6.2.2.7 Ovulidae
According to Wilson (1998) Ovulidae feed on the polyps of cnidarians and belong
thus to the guild of carnivorous grazers and they are considered to be parasites
sometimes. They belong to Cypraeoidea and have the convolute shell with genera
like Cypraea. They are of moderate diversity (400 species according to Lorenz
2005) and most species occur in the tropical Indo-Pacific.
Ovulidae originate at the latest in the Late Cretaceous according to Tracey
et al. (1993).
6.2.3 Functional Shell Morphology
Functional shell morphology is a potential tool to infer parasitism in fossil gastropods. However, this has not been explored and functional morphology of the gastropod shell is generally not well understood. As outlined above, the ratchet sculpture
of triphorids and cerithiopsids as well as their anteriorly constricted and rounded
shell may facilitate intrusion into the tissue of the host (Fig. 6.5). The extremely
smooth, polished shell with very shallow sutures of many eulimids (Fig. 6.2a, d)
forms certainly an adaptation regarding the parasitic life style. This shell morphology is also present in Palaeozoic subulitoid gastropods, such as Ceraunocochlis
(Fig. 6.2b, c); it is a reasonable speculation that such fossil gastropods were parasitic too (see below).
Gahn and Baumiller (2006) argued that the elongation of the anal tubes of
Palaeozoic crinoids had the function to hinder infestations by parasitic
platyceratids.
6 Gastropods as Parasites and Carnivorous Grazers: A Major Guild in Marine…
teeth per row. Within the group, the tooth morphology is extremely variable, some
having strongly elongated marginal teeth (e.g. Marshall 1978; Nützel 1998). It is
obvious that this represents an adaptation to the feeding on sponges but feeding
mechanisms have not been studied.
Cerithiopsidae sensu strictu are at least as old as Danian and are richly diversified
in the Danian Naesekalk from Denmark (Ravn 1933; Nützel 1998; Wesenberg and
Schnetler 2014) (Fig. 6.5f). The higher category Triphoroidea (respectively
Cerithiopsoidea) is older with a good fossil record from the Cretaceous and some
Jurassic representatives with the earliest record from the Bathonian (Nützel 1998
and references therein). The Triassic Protorculidae (earliest record Early Triassic,
Smithian) probably represent its fossil sister group (Nützel 1998; Nützel and
Erwin 2002).
6.2.2.7 Ovulidae
According to Wilson (1998) Ovulidae feed on the polyps of cnidarians and belong
thus to the guild of carnivorous grazers and they are considered to be parasites
sometimes. They belong to Cypraeoidea and have the convolute shell with genera
like Cypraea. They are of moderate diversity (400 species according to Lorenz
2005) and most species occur in the tropical Indo-Pacific.
Ovulidae originate at the latest in the Late Cretaceous according to Tracey
et al. (1993).
6.2.3 Functional Shell Morphology
Functional shell morphology is a potential tool to infer parasitism in fossil gastropods. However, this has not been explored and functional morphology of the gastropod shell is generally not well understood. As outlined above, the ratchet sculpture
of triphorids and cerithiopsids as well as their anteriorly constricted and rounded
shell may facilitate intrusion into the tissue of the host (Fig. 6.5). The extremely
smooth, polished shell with very shallow sutures of many eulimids (Fig. 6.2a, d)
forms certainly an adaptation regarding the parasitic life style. This shell morphology is also present in Palaeozoic subulitoid gastropods, such as Ceraunocochlis
(Fig. 6.2b, c); it is a reasonable speculation that such fossil gastropods were parasitic too (see below).
Gahn and Baumiller (2006) argued that the elongation of the anal tubes of
Palaeozoic crinoids had the function to hinder infestations by parasitic
platyceratids.
6 Gastropods as Parasites and Carnivorous Grazers: A Major Guild in Marine…