Predation of the Freshwater Crayfish Orconectes cristavarius by
the Fishing Spider Dolomedes scriptus
R. Katie Scott, Zachary W. Dillard, David A. Foltz, and Zachary J. Loughman
Southeastern Naturalist, Volume 15, Issue 3 (2016): N37–N39
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N37
2016 Southeastern Naturalist Notes Vol. 15, No. 3
R.K. Scott, Z.W. Dillard, D.A. Foltz, and Z.J. Loughman
Predation of the Freshwater Crayfish Orconectes cristavarius by
the Fishing Spider Dolomedes scriptus
R. Katie Scott1, Zachary W. Dillard1, David A. Foltz2, and Zachary J. Loughman1,*
Abstract - Herein we detail a predation event on Orconectes cristavarius (Spiny Stream Crayfish) by
Dolomedes scriptus (Striped Fishing Spider). On 12 July 2015, we discovered a female Striped Fishing
Spider along the banks of Knox Creek, Buckhannon County, VA, feeding on a young-of-the-year
Spiny Stream Crayfish. The spider had ingested the majority of the crayfish’s abdomen at the time of
discovery, and had used silk to anchor the crayfish to the undersurface of the rock where feeding was
taking place. We discuss the possible role of crayfish in the diet of Dolomedes spiders and provide a
detailed description of the spider ’s microhabitat.
Orconectes freshwater crayfish are confirmed prey items for various aquatic and
semiaquatic animals throughout North America. Several fishes, turtles, snakes, mammals,
and Cryptobranchus alleganiensis (Daudin) (Hellbender Salamander) have been
recorded as predators of Orconectes crayfish (Jezerinac et al. 1995, Pfleiger 1996, Taylor
and Shuster 2004); arthropods other than crayfish have not historically been recorded as
Orconectes predators. Here we describe an observed predation event on a young-of-theyear
Orconectes cristavarius (Taylor) (Spiny Stream Crayfish) by an adult Dolomedes
scriptus (Hentz) (Striped Fishing Spider; Family Pisauridae). The Striped Fishing Spider
is a large, semiaquatic fishing spider found throughout eastern and central North America
that frequents boulder fields and debris snags along larger-order stream banks (Bradley
2013, Carico 1973). Like other Dolomedes species, the Striped Fishing Spider is an opportunistic
predator that preys on small aquatic or terrestrial invertebrates and vertebrates.
This spider hunts for prey freely over water rather than capturing meals in a web (Barbour
1921, Carico 1973), discovering prey items through disruptions of surface tension of the
water (Bleckmann 1988). The Spiny Stream Crayfish is a freshwater crayfish endemic to
the central Appalachians’ Big Sandy, Guyandotte, Kentucky, and New river basins, where
it occurs in small streams to large rivers, often in considerable numbers (Taylor 2000,
Taylor and Shuster 2004).
We observed a female Striped Fishing Spider feeding on a young-of-the-year Spiny
Stream Crayfish along the banks of Knox Creek, Buckhannon County, VA, on 12 July
2015 at 15:30 h. We overturned the rock maintaining the spider and crayfish while we were
sampling for crayfish near the stream edge in a shallow (less than 25 cm), low-velocity run with
minimum canopy coverage (0–10%) and a low-gradient bank composed of several small
to moderately sized boulders. The spider was resting upside down on the undersurface of a
25 cm x 30 cm sandstone slab within 0.5 m of the stream. Substrate under the boulder was
composed of gravel and cobbles, as well as a small amount of spring-fed water that formed
a shallow eddy.
We could not determine where the spider made initial contact with its prey, though it
is likely that the eddy present under the rock where we found the spider was the place of
predation. Both the crayfish and spider were upside down near the outer margin of the slab
1West Liberty University, Department of Natural Sciences and Mathematics, 208 University Drive,
West Liberty, WV 26074. 2Civil and Environmental Consultants, Inc., 333 Baldwin Road, Pittsburgh,
PA 15205. *Corresponding author - zloughman@westliberty.edu.
Manuscript Editor: Bronwyn Williams
Notes of the Southeastern Naturalist, Issue 15/3, 2016
2016 Southeastern Naturalist Notes Vol. 15, No. 3
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R.K. Scott, Z.W. Dillard, D.A. Foltz, and Z.J. Loughman
(Fig. 1). The spider had employed silk threads (Fig. 1) to help anchor the crayfish to the
bottom of the rock. At the time of discovery, the female Striped Fishing Spider was grasping
the crayfish at the cephalthorax/abdomen junction with her chelicerae and fangs, with
the ventral surface of the crayfish facing her. The female spider’s chelicerae were bored
into the ventral side of the prey’s upper abdomen, and most of the telson and abdomen
of the crayfish had been ingested (Fig. 1). Following disturbance, the spider showed no
interest in releasing its prey, and remained motionless for our 10-min observation. We returned
the rock to its original placement so as not to further disturb the feeding event.
Fish predation by semi-aquatic spiders is geographically widespread (Carico 1973,
Nyffeler and Pusey 2014), and Dolomedes spp. (fishing spiders) frequently consume small
vertebrates (Carico 1973, Kissane 2001, Machado and Lipinski 2014). However, records
of freshwater crayfish predation by fishing spiders are rare. Figiel (1995) used juvenile
Procambarus sp. (crayfish) as prey for Dolomedes triton (Walckenaer) (Six-spotted Fishing
Spider) in a captive environment. Our observation may represent the first published predation
event of a Dolomedes species feeding on crayfish in a natural situation.
During certain times of the year, crayfish may represent an important food source for
Striped Fishing Spiders as well as other fishing spiders that prefer lotic waterways (i.e.,
Dolomedes vittatus Walckenaer and Dolomedes tenenbrosus Hentz [Dark Fishing Spider]).
Many crayfish in the genus Orconectes employ a life-history strategy that involves
saturating streams with large numbers of young-of-the-year individuals in April through
June (Moore et al. 2013, Taylor and Shuster 2004). Juvenile crayfish seek out slack-water
environments and are frequently encountered near stream margins and within shallow eddies
along runs and pools (Jezerinac et al. 1995, Taylor and Shuster 2004) and also frequent
Figure 1. Dolomedes scriptus with young of the year Orconectes cristavarius as prey.
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2016 Southeastern Naturalist Notes Vol. 15, No. 3
R.K. Scott, Z.W. Dillard, D.A. Foltz, and Z.J. Loughman
shallow pools isolated from main channels during periods of drawdown. All of these environments
are confirmed hunting locations of lotic fishing spiders. Dolomedes spiders are
probably alerted to the presence of crayfish by the high level o f activity of the latter.
It seems that crayfish would be able to fend off an attack through use of their chelipeds.
However, if fishing spiders engage crayfish with the same strategy described for fish predation,
in which the spiders grasp fishes in the back of the head and wrap their legs around
their prey, the chelipeds of crayfish could be easily rendered useless following a venomous
bite (Nyffler and Pusey 2014). Further investigation is needed t o determine the overall importance
of crayfish as prey for fishing spiders, as well as any impacts this predation may
have on young-of-the-year crayfish cohorts. Crayfish are the largest freshwater arthropods
in North America; it is only fitting that one of the largest araenomoprh spiders in North
America has now been confirmed to include them as prey .
Acknowledgments. We thank David Howard, Troy Hubbard, Luke Sadecky, and Nicole Sadecky
for assistance in the field.
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