219
(1987) (Pyramidelloidea), that are considered to be parasites on bivalves today,
were reported by Kaim (2004) from the Early Cretaceous.
6.2.2.5 Architectonicidae and Mathildidae
Architectonicidae are considered to be ectoparasites of colonial cnidarians such as
zoantharian, scleractinian and antiparian corals (Healey 1998b and references
therein). They show buccal and radular specializations for feeding on hexacorallian
coelenterates such as stony corals, sea anemones and zoanthids (Bieler and Petit
2005). A large number of species names have been proposed but according to Bieler
and Petit (2005) only about 140 extant species are valid. Their attractive shells are
conical and comparatively low-spired (some even planispiral) with an umbilicated
base—thus they are unlike most other parasitic gastropod according to shell morphology. Their shell morphology resembles that of Trochidae but they can be separated from them by having a heterostrophic larval shell and lacking nacre.
Bandel (1988) placed two Late Triassic (Carnian) genera (Amphitomaria and
Rinaldoconchus) from the Cassian Formation in Architectonicidae which represents
their first appearance date according to the current state of knowledge (Tracey et al.
1993). Attributions of Palaeozoic shells to Architectonicidae are erroneous (Bieler
and Petit 2005).
Architectonicidae and the high-spired Mathildoidea are considered to be closely
related and are sometimes placed in the same superfamily or as separate superfamilies. Mariottini et al. (2009) stated that “these mollusks are associated to cnidarians
for feeding habit”. However, the feeding habit of this group is poorly known. If
Mathildidae are parasitic or have a similar life style, it would be an important group
representing this guild, especially in the Mesozoic. Mathildidae are richly diversified during the Mesozoic at least from the Late Triassic onward and are still present
today but more in deeper water environments than in shallow water as it used to be
earlier (Bandel 1995; Gründel and Nützel 2013; Bieler 1995). In the Late Triassic
Cassian Formation, Mathildidae were much more diverse and abundant than in any
site today.
6.2.2.6 Triphoridae and Cerithiopsidae: Carnivorous Grazers
(Sponge Feeders)
Triphoridae and Cerithiopsidae are super-diverse gastropod groups that live on
sponges (Fig. 6.5). They actually feed on sponge tissue of demosponges—stomach
and fecal pellets may contain sponge spicules (Nützel 1998; Fig. 6.6). They also
feed on mucous on the sponges. There are observations for some living species that
individuals are attached to sponges with mucous threads and that they deposit spawn
on or within sponges (Nützel 1998; Fernandes and Pimenta 2019; see Fig. 6.6).
Lorenz (2005) reported cypraeid egg clusters in sponges. So in a wider sense,
Triphoridae and Cerithiopsidae can be considered ectoparasites, living on their host
6 Gastropods as Parasites and Carnivorous Grazers: A Major Guild in Marine…
(1987) (Pyramidelloidea), that are considered to be parasites on bivalves today,
were reported by Kaim (2004) from the Early Cretaceous.
6.2.2.5 Architectonicidae and Mathildidae
Architectonicidae are considered to be ectoparasites of colonial cnidarians such as
zoantharian, scleractinian and antiparian corals (Healey 1998b and references
therein). They show buccal and radular specializations for feeding on hexacorallian
coelenterates such as stony corals, sea anemones and zoanthids (Bieler and Petit
2005). A large number of species names have been proposed but according to Bieler
and Petit (2005) only about 140 extant species are valid. Their attractive shells are
conical and comparatively low-spired (some even planispiral) with an umbilicated
base—thus they are unlike most other parasitic gastropod according to shell morphology. Their shell morphology resembles that of Trochidae but they can be separated from them by having a heterostrophic larval shell and lacking nacre.
Bandel (1988) placed two Late Triassic (Carnian) genera (Amphitomaria and
Rinaldoconchus) from the Cassian Formation in Architectonicidae which represents
their first appearance date according to the current state of knowledge (Tracey et al.
1993). Attributions of Palaeozoic shells to Architectonicidae are erroneous (Bieler
and Petit 2005).
Architectonicidae and the high-spired Mathildoidea are considered to be closely
related and are sometimes placed in the same superfamily or as separate superfamilies. Mariottini et al. (2009) stated that “these mollusks are associated to cnidarians
for feeding habit”. However, the feeding habit of this group is poorly known. If
Mathildidae are parasitic or have a similar life style, it would be an important group
representing this guild, especially in the Mesozoic. Mathildidae are richly diversified during the Mesozoic at least from the Late Triassic onward and are still present
today but more in deeper water environments than in shallow water as it used to be
earlier (Bandel 1995; Gründel and Nützel 2013; Bieler 1995). In the Late Triassic
Cassian Formation, Mathildidae were much more diverse and abundant than in any
site today.
6.2.2.6 Triphoridae and Cerithiopsidae: Carnivorous Grazers
(Sponge Feeders)
Triphoridae and Cerithiopsidae are super-diverse gastropod groups that live on
sponges (Fig. 6.5). They actually feed on sponge tissue of demosponges—stomach
and fecal pellets may contain sponge spicules (Nützel 1998; Fig. 6.6). They also
feed on mucous on the sponges. There are observations for some living species that
individuals are attached to sponges with mucous threads and that they deposit spawn
on or within sponges (Nützel 1998; Fernandes and Pimenta 2019; see Fig. 6.6).
Lorenz (2005) reported cypraeid egg clusters in sponges. So in a wider sense,
Triphoridae and Cerithiopsidae can be considered ectoparasites, living on their host
6 Gastropods as Parasites and Carnivorous Grazers: A Major Guild in Marine…