About

Armand Kuris is a professor in the Department of Ecology, Evolution, and Marine Biology at UC Santa Barbara. His laboratory engages in research across four interlocking areas, focusing on the nature of adaptive peaks for various trophic interactions within food webs, including predator/prey and parasite/host relationships. His work expands the concept of parasitic castration as a distinct trophic phenomenon and has led to numerous applications, such as understanding interactions between larval trematodes, their impact on fisheries, and the development of biological control methods for marine pests and human schistosomiasis. Kuris's research involves extensive field work in salt marshes, studying larval trematode parasitic castrators that are strong interactors in snail hosts. His team uses molecular tools to investigate transmission dynamics and spatial heterogeneity, including the movement of final hosts like birds. His studies also include in vitro competition experiments and behavioral modifications in parasite transmission. He has contributed to models predicting how infectious diseases can cause significant losses in fisheries and has been involved in managing crab fisheries through disease control strategies. Since 1993, he has worked on biocontrol programs targeting the European green crab and the sabellid pest affecting mollusks, assessing host-specificity, shell damage mechanisms, and distribution. Additionally, Kuris has been involved in efforts to control human schistosomiasis through ecological interventions, notably demonstrating the effectiveness of Louisiana crayfish in blocking disease transmission, which led to a significant reduction in infection prevalence among school children. His work aims to expand funding and develop appropriate ecological technologies to combat tropical diseases and manage marine pests.

Research topics

• Zoology
• Biology
• Ecology
• Geography
• Fishery
• Economics
• Evolutionary biology
• Genetics

Selected publications

• Discovery of an unidentified species of nicothoid copepod infesting cancrid crabs in Santa Barbara, California

  Ecology · 2025-12-01

  articleOpen access

  Externally brooding crustaceans host a variety of symbiotic egg predators, often causing substantial brood mortality (Kuris et al., 1991; Kuris & Wickham, 1987). Taxa known to live and feed on crustacean eggs (summarized by Kuris, 1993) include various microorganisms, rotifers, gastropods, worms (nemerteans, turbellarians, nematodes, polychaetes, and oligochaetes), and other small crustaceans (copepods, amphipods, and isopods). Heavy infestations of egg predators, for example, nemertean worms in the Dungeness crab, Metacarcinus magister, have been implicated in the collapse (Wickham, 1979, 1986) and slow recovery (Hobbs & Botsford, 1989; Kuris et al., 1991) of some crustacean fisheries. The copepod family Nicothoidae includes parasites and symbiotic egg predators of other crustaceans, most of which have adopted egg mimicry as a life history strategy (Boxshall & Halsey, 2004). High intensities of nicothoids have negatively impacted the fecundity of commercially important species, such as the blue sand crab in Australia (Shields & Wood, 1993). In October 2021, during a routine classroom laboratory activity at the University of California Santa Barbara focused on the demonstration of crustacean egg predators, we observed, for the first time, a nicothoid copepod in the genus Choniosphaera Connolly, 1929 infesting ovigerous yellow rock crabs (Metacarcinus anthonyi Rathbun, 1897). This discovery prompted further investigation, during which crabs were collected by fishermen from a 66–100 m depth using baited crab pots along the Gaviota Coast, west of Santa Barbara, CA (see Appendix S1: Section S1 for full methods). Crabs were held in flow-through aquaria during the investigation. We discovered Choniosphaera sp. in abundance on two other commercially important rock crab species, Romaleon antennarium Stimpson, 1856 and Cancer productus Randall, 1840. These crabs are habitat generalists, occurring in coastal waters from 0 to 150 m, and together form a small fishery in California (CDFW, 2019; Morris et al., 1980). Four species of nicothoids have been reported in association with seven species of brachyuran crabs, with varying effects on host fecundity (Bloch & Gallien, 1933; Connolly, 1929; Dang et al., 2022; Fischer, 1956; Gnanamuthu, 1954; Johnson, 1957; Santos & Björnberg, 2004; Shields & Wood, 1993). Nicothoid copepods have not been previously reported infesting decapod species from the Eastern Pacific (Appendix S1: Figure S1) despite extensive inspection of cancrid egg clutches during studies of the egg-predatory nemertean Carcinonemertes epialti Coe, 1902 in the 1990s (Shields et al., 1990, 1991). Furthermore, the University of California Santa Barbara Invertebrate Biology undergraduate class and instructors have carefully inspected cancrid egg masses for symbiotic egg predators annually since 1978. This study documents the first detection of a nicothoid copepod in these examinations. Members of two nicothoid genera, Choniosphaera and Carcinothoe, are reported to infest brachyuran crab egg masses (Bloch & Gallien, 1933; Connolly, 1929; Fischer, 1956; Lee & Kim, 2024). The nicothoid discussed herein is more closely aligned with Choniosphaera based on adult female morphological characteristics, including a globular shape with no abdomen, distinctly ventrally positioned mouthparts, a biarticulate exopod and uniarticulate endopod on legs 1 and 2, antennules with 11 segments, and a caudal ramus with four to five setae (Bloch & Gallien, 1933; Connolly, 1929; Lee & Kim, 2024). The adult female nicothoid was the first life stage we observed on crab eggs (Figure 1a). We did not observe any adult nicothoids that we could recognize as male, and the apparent lack of male Choniosphaera sp. warrants further investigation. Adult females of Choniosphaera sp. appear to live permanently on the egg masses of their crab hosts and as such, their morphology is highly modified. The adult female body is globular and not visibly segmented. Its shape is similar to the host's eggs, and it camouflages well with the egg mass (Figure 1b; Appendix S1: Figure S3). Adult female Choniosphaera sp. change coloration as they increase in size and become gravid (Figure 1, see also Adult_Nicothoid_Video.MOV in Orli et al., 2025b). Adult nicothoids found on host egg masses that are in early developmental stages range in color from yellow to orange, while adults found on later stage egg masses are maroon (Figure 1a, see Appendix S1: Table S1 for a description of host egg developmental stages). We observed that adult female Choniosphaera sp. increase in size without molting, which is a phenomenon that has been documented for other symbiotic copepod females (Kabata, 1979; Ohtsuka et al., 2004, 2005; Smith & Whitfield, 1988). When adult females of Choniosphaera sp. were removed from the host eggs, all died within 24 h despite being kept well aerated in flow-through seawater and provided with eggs to feed on. The Choniosphaera sp. life cycle appears to be coupled with host crab egg development (Appendix S1: Figure S2). Throughout the duration of host egg development (approximately 45 days for M. anthonyi; see Appendix S1: Table S1), adult females of Choniosphaera sp. oviposit egg sacs, carrying between one and four egg sacs at a time. As the females move throughout the host egg mass, their egg sacs become tangled among the host's eggs (Figure 1d). Each sac contains one to four embryos (Figures 1b and 2a). We were unable to track the number of eggs deposited per female throughout host egg development because it was impossible to distinguish individual nicothoids in situ, and the tendency of females to die when removed from the host's egg mass prohibited prolonged observation ex situ. The nicothoid copepod examined in this study follows a life cycle similar to the other two Choniosphaera species, Choniosphaera cancrorum and Chonios. maendis (Bloch & Gallien, 1933; Connolly, 1929). Of the 22 genera in the family Nicothoidae, only two genera, Choniosphaera and Choniomyzon, contain species where eggs hatch into nauplii (Wakabayashi et al., 2013). Once nauplii hatch from the egg sac (Figure 2b), they develop more appendages and increased segmentation through an unknown number of sequential molts until they reach the first copepodid stage, which is characterized by well-developed swimming legs (Figure 2d). The density of copepodids peaks near the end of host egg development (Appendix S1: Figure S2). Copepodids were observed feeding on host eggs. Once the crab zoeae hatch from the host crab egg mass, the female crab removes old egg shells, aborted eggs, and debris from her pleopods (as noted by Shields et al., 1991), presumably including all nicothoids remaining on the egg mass. However, we also observed copepodids among host crab gill lamellae both before and after host egg hatching (Figure 2e). Other symbiotic egg predators of crabs (Kuris, 1993) have been reported from host gills, notably including a nicothoid, Carcinothoe indica, that is closely related to the species described herein (reported as Choniosphaera indica in Shields & Wood, 1993). We detected nicothoids in the egg masses of seven crabs that oviposited a subsequent clutch of eggs while under observation. Copepodid larvae were observed in these crabs' egg masses within a day of oviposition, and adult Choniosphaera sp. were present within 9 days (Appendix S1: Figure S2). Based on these observations, we speculate that copepodids migrate to the gills to wait for their host's next oviposition, but we did not observe copepodids moving from the host egg mass to the host gills. In at least one other nicothoid species, subadult females have been observed migrating through the host body (Ohtsuka et al., 2007). We also recovered copepodids in the gills of male host crabs, suggesting that the copepodid stage may be able to disperse to new hosts and that male crabs may serve as reservoir hosts (Appendix S1: Table S2). The nauplii could also potentially disperse, but because of their lack of developed swimming legs, they would likely require physical contact between hosts to do so (Figure 2b). We observed Choniosphaera sp. in R. antennarium, M. anthonyi, and Can. productus egg masses from Santa Barbara, CA, and San Diego, CA. Nearly all crabs of both sexes, for all three species examined, had at least one life stage of nicothoid in their gills, their egg masses, or both (Appendix S1: Table S2). All ovigerous M. anthonyi and the majority of the other two ovigerous cancrids examined had reproductive nicothoid adults present in the egg mass. The only crabs uninfested by any nicothoid life stages (including the gills) were two juveniles, a non-ovigerous female, and two males that had been housed for over 6 months (Appendix S1: Table S2). It is possible that copepodids cannot survive in the gills indefinitely and that they must feed on egg yolk in order to reach adulthood, which would explain the observed loss of infection in male crabs. The lack of nicothoids in juvenile crabs leads us to hypothesize that nicothoids do not colonize potential hosts until the crabs are sexually mature. It is noteworthy that a distinctive nicothoid egg predator suddenly appeared in abundance on cancrid crabs in the Santa Barbara area. Nicothoid copepods had never been observed despite their distinctive appearance. This discovery suggests two mutually exclusive explanations: either this is an exotic introduction, or it is a native species which had previously existed unobserved on other crabs and has now transferred to a new group of hosts. The exotic hypothesis is unlikely because no congeneric nicothoid is known from the Indo-Pacific region, temperate, or boreal Pacific waters. A species in the similar genus Choniomyzon (D. Tang, personal communication) is common on Portunus pelagicus from India to Australia. However, historical studies on the two Atlantic species of Choniosphaera best support the hypothesis that nicothoids are native but perhaps ephemeral, emerging in abundance episodically over a time scale of decades. Choniosphaera maenadis was discovered on Carcinus maenas, the common and well-studied European shore crab, at Wimereux, Normandy in the mid-1930s (Bloch & Gallien, 1933; Gallien & Bloch, 1936), and reported from Whitstable, England, about 100 km from Wimereux by Gordon (Needham, 1933). It was not reported again until the 1950s from the North Sea, Germany (Fischer, 1956), and Norfolk, England in 1959 (Hamond, 1973). In both instances, Chonios. maenadis appears to have become locally abundant only to never be reported again (see also Stentiford, 2008). Similarly, in New England and the Canadian Maritimes, Chonios. cancrorum has been reported only twice, many years apart (Connolly, 1929; Johnson, 1957). The presence of Choniosphaera sp. represents a threat to the under-managed and data-poor California rock crab fishery (Fitzgerald et al., 2018). An egg predator that is present in 100% of the breeding host population will likely impact population fecundity (see Appendix S1: Section S2 for further discussion). At the time that Chonios. cancrorum was discovered in the brood of Carcinus maenas in New England, the effect of Chonios. cancrorum was notable enough to garner hope for its use as a biological control of that invasive pest species (Johnson, 1957). The discovery of this novel egg predator in Southern California could have a deleterious effect on the Santa Barbara rock crab fishery and the general role of these cancrids as predators in nearshore subtidal habitats. Notably, these nicothoids add to brood losses caused by Carcinonemertes sp. nemertean egg predators (Shields et al., 1990). The sudden emergence of an epizootic of nicothoid egg predators combined with a robust population of existing egg predators warrants further research on their impact on the fecundity of host populations. Our research team is currently quantifying egg mortality rates in infested egg masses. Further research should focus on revealing the current geographical extent of the nicothoid outbreak and the diversity of its host range among Eastern Pacific crabs. This project would not have been possible without Julia Vaughan, Kaytlin Troxler, Dakota Tyson, Annika Sullivan, Isabella Check, Yinghui Wang, Sawyer Kennedy, and Nathaniel Price for their help with laboratory work, Juli Passerelli at the Southern California Academy of Sciences for her copepod expertise, Steve Escobar, Carrie Culver, Christoph Pierre, and Christian Orsini for obtaining crabs, Ryan Hechinger and Emma Palmer at Scripps Institute of Oceanography for discovering this nicothoid in San Diego, and the Partnership for Interdisciplinary Studies of Coastal Oceans and Chris Honeyman for the use of their equipment. This project was funded by the University of California Santa Barbara Coastal Fund. The authors declare no conflicts of interest. Data and code (Orli et al., 2025a) are available in Dryad at https://doi.org/10.5061/dryad.rv15dv4fw. Video files (Orli et al., 2025b) are available in Zenodo at https://doi.org/10.5281/zenodo.10699477. Appendix S1. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

  PublisherDOI

• Phylum Platyhelminthes

  Elsevier eBooks · 2025-01-01

  book-chapter
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• Contributors

  Elsevier eBooks · 2025-01-01

  book-chapter
  PublisherDOI

• A parasite-inclusive food web for the California rocky intertidal zone

  Scientific Data · 2024-10-17

  preprintOpen accessSenior author

  We present a highly resolved, species-rich food web, including parasitic interactions, for the California rocky intertidal zone. The food web, which is a meta-web inclusive of all rocky intertidal taxa in California, is comprised of 1994 nodes, representing 1901 taxa, and 15,485 links that illustrate trophic interactions between nodes. While only 4.4% of links represent parasitic interactions, we have assembled possibly the most speciose parasite-inclusive food web ever published. The inclusion of all nodes and links are justified using multiple lines of evidence which are built into the dataset. In addition, metadata, including trophic strategy, taxonomic information, habitat, and other ecological attributes allow the data user to filter the food web to their specifications. The food web is a powerful and flexible tool for researchers with questions about large network properties, ecological dynamics of rocky shores, and the role of parasites in ecosystems. Our food web can be used to predict how complex ecosystems like the California rocky intertidal will respond to anthropogenic change and management strategies.

  PublisherOA PDFDOI

• Parasites alter food-web topology of a subarctic lake food web and its pelagic and benthic compartments

  Oecologia · 2024-02-01 · 6 citations

  articleOpen access

  We compared three sets of highly resolved food webs with and without parasites for a subarctic lake system corresponding to its pelagic and benthic compartments and the whole-lake food web. Key topological food-web metrics were calculated for each set of compartments to explore the role parasites play in food-web topology in these highly contrasting webs. After controlling for effects from differences in web size, we observed similar responses to the addition of parasites in both the pelagic and benthic compartments demonstrated by increases in trophic levels, linkage density, connectance, generality, and vulnerability despite the contrasting composition of free-living and parasitic species between the two compartments. Similar effects on food-web topology can be expected with the inclusion of parasites, regardless of the physical characteristics and taxonomic community compositions of contrasting environments. Additionally, similar increases in key topological metrics were found in the whole-lake food web that combines the pelagic and benthic webs, effects that are comparable to parasite food-web analyses from other systems. These changes in topological metrics are a result of the unique properties of parasites as infectious agents and the links they participate in. Trematodes were key contributors to these results, as these parasites have distinct characteristics in aquatic systems that introduce new link types and increase the food web's generality and vulnerability disproportionate to other parasites. Our analysis highlights the importance of incorporating parasites, especially trophically transmitted parasites, into food webs as they significantly alter key topological metrics and are thus essential for understanding an ecosystem's structure and functioning.

  PublisherOA PDFDOI

• Parental care reduces parasite-induced mortality in a coral reef fish

  Proceedings of the Royal Society B Biological Sciences · 2024-10-01 · 1 citations

  articleOpen accessSenior author

  Settlement patterns of juvenile fish shape coral reef communities. During the recruitment process, predation rates are extremely high. However, the role that parental care plays in reducing mortality, especially by cryptic natural enemies such as parasites, remains largely unstudied. We investigated whether parental care in the spiny chromis damselfish ( Acanthochromis polyacanthus ) protects juveniles from parasite-induced mortality by gnathiid isopods ( Gnathia aureamaculosa ). Using laboratory experiments, we found that survival of recently hatched juveniles when exposed to gnathiids was higher when parents were present (77%) than when parents were absent (25%). Investigation of their faeces in the field and laboratory indicates that adults consume gnathiids. Together, our data suggest that parental care plays a key role in reducing parasite-induced mortality of juvenile spiny chromis via parental consumption of gnathiids. This highlights the overlooked role of parasites as a source of high mortality in juvenile coral reef fishes and the composition of coral reef fish communities.

  PublisherOA PDFDOI

• Intertidal Parasites and Commensals

  2023-09-01

  book-chapter1st authorCorresponding
  PublisherDOI

• Acanthocephala

  2023-09-01

  book-chapter1st authorCorresponding
  PublisherDOI

• Raymond Gibson (1938–2023): in memoriam

  Zootaxa · 2023-07-02

  articleOpen access

  N

  PublisherOA PDFDOI

• Science fiction: The biology of the alien in <i>Alien</i>

  The Biochemist · 2023-12-19

  articleOpen access1st authorCorresponding

  Parasites serve as a source of threatening outcomes for humans in many science fiction plots. Perhaps the most notable is the Xenomorph of the first Alien film (1979). Here, we use the film as the sole source of direct information to hypothesize its life cycle. We recognize a distinctive infective stage, the face-hugger. To further its development as an internal parasite in its human host, we conceive features of its physiology. It has an astonishing ability to manipulate the behaviour of its doomed host, before emerging as the famous chest-burster. It is clearly a parasitoid, requiring the death of its host. A further metamorphosis completes its development to the adult predator that roams the doomed spaceship Nostromo. The Xenomorph adult stage bears an uncanny resemblance to a parasitoid of salps, pelagic invertebrates. Conceptualizing its mythic biology offers insight into the physiology and biochemistry of real parasites.

  PublisherOA PDFDOI

Recent grants

• Anthropogenic Effects on Host-Trematode Dynamics

  NSF · $2.2M · 2002–2009

• CNH: The Coupled Human Health and Environmental Dynamics of Schistosomiasis

  NSF · $1.5M · 2014–2020

• DISSERTATION RESEARCH:Understanding effects on climate change on parasitism in small mammals

  NSF · $20k · 2016–2018

• Collaborative Research: Modeling Infectious Diseases: How Much Ecological Complexity Must We Address?

  NSF · $2.1M · 2011–2017

Frequent coauthors

• Kevin D. Lafferty

  United States Geological Survey

  182 shared

• Sara B. Weinstein

  Utah State University

  52 shared

• Camille Lake

  National Institutes of Health

  49 shared

• Holly M. Chastain

  49 shared

• Susan P. Montgomery

  Centers for Disease Control and Prevention

  49 shared

• David Fisk

  Sansum Medical Clinic

  49 shared

• Patricia P. Wilkins

  49 shared

• Sukwan Handali

  49 shared

Labs

• Parasite Ecology GroupPI