212
The highly diverse generally small-sized Cerithiopsidae and sinistrally coiled
Triphoridae (Triphoroidea) feed on sponges obviously without necessarily killing
their prey. These spongivorous gastropods are not considered to represent parasites
in a strict sense but carnivorous grazers and their relationship to sponges resembles
parasitism. It is also likely that they feed on microbial biofilms and mucous associated with the sponges. They probably encompass several thousand living species.
Cerithiopsidae and Triphoridae were placed in the heterogeneous, probably notmonophyletic group Ptenoglossa together with Epitoniidae and Eulimidae (e.g.,
Nützel 1998). Takano and Kano (2014) showed based on a molecular phylogeny
that Ptenoglossa in their traditional composition are polyphyletic and that Eulimidae
are the sister group of carnivorous Vanikoridae.
The census of a marine area at Koumac, an intensively studied coastal site in
New Caledonia, undertaken by Bouchet et al. (2002) shows how important parasitic
gastropods are in modern tropical environments. These authors counted a total of
2187 mollusk species, 270 (ca. 12%) of which belong to the parasitic Eulimidae (the
third most diverse family) and Pyramidellidae (the fourth most species-rich family).
The spongivorous Triphoridae and Cerithiopsidae represent the second and fifth
most diverse mollusk families. Similarly, a census from the coral triangle (Panglao,
Philippines) resulted in the finding of at least 715 species of Pyramidellidae from an
area of 15,000 ha (150 km
2
) and the real number there may exceed 1100 species
(Bouchet 2009). Most of these species are small (41% have adult sizes equal or
below 2 mm) (Bouchet 2009). Besides Pyramidellidae, the parasitic Eulimidae and
sponge-associated Cerithiopsidae and Triphoridae belong the most diverse groups.
6.2 How to Infer Parasitism in Fossil Gastropods
There are several lines of evidence to infer parasitism (see also Boucot 1990; Nagler
and Haug 2015): (1) direct evidence i.e., observation of parasite and prey/host associations or traces of parasitism on fossil prey, (2) taxonomic uniformitarianism i.e.,
the fossil record of extant parasitic gastropod groups, usually on the family or genus
level, (3) functional shell morphology i.e., a shell morphology that is suggestive of
parasitism, and connected with this (4) analogy of associated phenomena e.g., the
observation that modern parasitic gastropod families generally consist of small,
high-spired and highly diverse groups with low disparity can be transferred to
extinct groups that show similar properties.
6.2.1 Direct Observations
Direct observations of parasitism in fossil gastropods are rare. Baumiller and Gahn
(2002) reported about 30 cases of parasitism from the fossil record, seven of which
involved gastropods as parasites. One of the most famous examples is the
A. Nützel
The highly diverse generally small-sized Cerithiopsidae and sinistrally coiled
Triphoridae (Triphoroidea) feed on sponges obviously without necessarily killing
their prey. These spongivorous gastropods are not considered to represent parasites
in a strict sense but carnivorous grazers and their relationship to sponges resembles
parasitism. It is also likely that they feed on microbial biofilms and mucous associated with the sponges. They probably encompass several thousand living species.
Cerithiopsidae and Triphoridae were placed in the heterogeneous, probably notmonophyletic group Ptenoglossa together with Epitoniidae and Eulimidae (e.g.,
Nützel 1998). Takano and Kano (2014) showed based on a molecular phylogeny
that Ptenoglossa in their traditional composition are polyphyletic and that Eulimidae
are the sister group of carnivorous Vanikoridae.
The census of a marine area at Koumac, an intensively studied coastal site in
New Caledonia, undertaken by Bouchet et al. (2002) shows how important parasitic
gastropods are in modern tropical environments. These authors counted a total of
2187 mollusk species, 270 (ca. 12%) of which belong to the parasitic Eulimidae (the
third most diverse family) and Pyramidellidae (the fourth most species-rich family).
The spongivorous Triphoridae and Cerithiopsidae represent the second and fifth
most diverse mollusk families. Similarly, a census from the coral triangle (Panglao,
Philippines) resulted in the finding of at least 715 species of Pyramidellidae from an
area of 15,000 ha (150 km
2
) and the real number there may exceed 1100 species
(Bouchet 2009). Most of these species are small (41% have adult sizes equal or
below 2 mm) (Bouchet 2009). Besides Pyramidellidae, the parasitic Eulimidae and
sponge-associated Cerithiopsidae and Triphoridae belong the most diverse groups.
6.2 How to Infer Parasitism in Fossil Gastropods
There are several lines of evidence to infer parasitism (see also Boucot 1990; Nagler
and Haug 2015): (1) direct evidence i.e., observation of parasite and prey/host associations or traces of parasitism on fossil prey, (2) taxonomic uniformitarianism i.e.,
the fossil record of extant parasitic gastropod groups, usually on the family or genus
level, (3) functional shell morphology i.e., a shell morphology that is suggestive of
parasitism, and connected with this (4) analogy of associated phenomena e.g., the
observation that modern parasitic gastropod families generally consist of small,
high-spired and highly diverse groups with low disparity can be transferred to
extinct groups that show similar properties.
6.2.1 Direct Observations
Direct observations of parasitism in fossil gastropods are rare. Baumiller and Gahn
(2002) reported about 30 cases of parasitism from the fossil record, seven of which
involved gastropods as parasites. One of the most famous examples is the
A. Nützel