Biology Reference
In-Depth Information
(A)
(B)
Plate 2.11
(A and B) The enlarged anterior maxillary dentition of the emerald tree
boa (
Corallus caninus
).
Although the teeth are enlarged and recurved (arrows), there are
no grooves or other modifications. These teeth are probably used in order to aid grasping
or stabilizing prey. These arboreal snakes can inflict a painful wound including edema and
erythema. Therefore, a bite by a snake with large teeth and lacking oral secretions of any
appreciable toxicity can still produce mild local effects as a result of purely physical trauma.
AMNH specimen #R57788, photo copyright to Arie Lev.
who have maintained captive specimens of this attractive species. However, there
may be no apparatus for producing or administering any specialized oral secretion.
Henophidians, such as
C. caninus
, lack Duvernoy's glands as well as “true” venom
glands; thus, they are truly nonvenomous and do not produce “mildly toxic saliva.”
2
Therefore, it is important to remain aware that physical trauma inflicted from bites by
snakes with large teeth, and without toxic secretion, can be incorrectly assigned with a
“toxic” potential due to misinterpretation of localized trauma (see later).
In some species, evidence suggests that prey preference may influence the specific
nature of specialized dentition, and these adaptive modifications may facilitate prey han-
dling. Lizards with tightly overlapping scales [e.g., those with cycloid scales, such as
scincid lizards (skinks)] may present as hard-bodied prey items that are difficult to grasp.
Modified teeth may serve to maintain a firm grip, prevent escape, and aid deglutition. In
some species, such as the common wolf snake (
Lycodon aulicus capucinus
), the com-
bination of several dentitional modifications [e.g., enlarged anterior maxillary teeth, an
arched maxilla, and enlarged (ungrooved) posterior maxillary teeth] may increase the
likelihood of successful prey capture, control, and ingestion (Jackson and Fritts, 2004).
In other species (e.g., the Asian mock viper or leopard snake,
Psammodynastes pulveru-
lentus
), dentitional adaptations are probably used in concert with Duvernoy's secretions
in order to subjugate prey (Savitzky, 1983; see later). The Asian slug-eating snakes (fam-
ily Pareatidae) comprise a group of gastropod specialists (or “malacophagous” snakes)
with a distinct lineage (Vidal et al., 2007). Some of these snakes (e.g.,
Pareas iwasakii
;
2
Antiserums against venoms from elapids such as
Dendroapsis
spp. (mambas),
Naja
spp., and
Haemachatus
haemachatus
(ringhals, ringhals spitting cobra) have shown some limited immunoelectrophoretic cross-
reactivity with oral secretions from the Bahaman boa,
Epicrates striatus strigilatus
(Eleuthera Island boa; see
Minton and Weinstein, 1987). Although it has no medical or apparent biological significance, the phenom-
enon may reflect “exaptation” or “preadaptation.” This is discussed later in relation to consideration of toxins
present in the oral secretions of nonvenomous lizards.
