Planktonic associations between medusae (classes Scyphozoa and Hydrozoa) and epifaunal crustaceans

Abstract

Jellyfish are known to carry various epibionts, including many of the subphylum Crustacea. However, the associations between gelatinous zooplankton and other invertebrates have been chronically overlooked. Crustacea, a massive clade of economically, ecologically, and culturally important species, includes many taxa that utilize gelatinous zooplankton for food, transport, and protection as both adults and juveniles. Here we compile 211 instances of epifaunal crustaceans recorded on Hydromedusae and Scyphomedusae from a century of literature. These include 78 identified crustacean species in 65 genera across nine orders found upon 37 Hydromedusa species and 48 Scyphomedusae. The crustacean life stage, location, nature of the association with the medusa, years, months, and depths are compiled to form a comprehensive view of the current state of the literature. Additionally, this review highlights areas where the current literature is lacking, particularly noting our poor understanding of the relationships between juvenile crabs of commercially valuable species and medusae.

Keywords: Association; Commensal; Crustacea; Epifauna; Hydrozoa; Jellyfish; Marine; Medusa; Scyphozoa.

Figure 1. Summary of Google Search Results.

The number of results reported by Google Scholar Advanced Search where both “Crustacea” and one of the four medusa describer terms was included (“Hydrozoa”, “Scyphozoa”, “medusa”, or “jellyfish”) and at least one of the following terms was included (Association, Associated, Symbiotic, Symbiosis, Commensal, Epifaunal, Harboring, Parasitic, Parasitoid, Epibiont or Epibiotic).

Figure 2. Diversity of Scyphozoa and Hydrozoa species.

Rings from innermost to outermost are order, family, genus in the classes (A) Scyphozoa and (B) Hydrozoa as distributed by number of accounts including a host in that group. Families and genera with single reports are whitened.

Figure 3. Diversity of Crustacean epibionts.

From innermost ring to outermost ring: Subphylum, Order, Family, Genus. Color coded by classes Malacostraca (orange), Hexanauplia (pink), and Brachipoda (green). Families and genera reported only once are whitened.

Figure 4. Collections information for both number of papers using a collection method and number of associations reported from this collection type.

Types are blue water diving (BWD), collection by hand (HC), multiple methods (MULTI), ring net (RN), scuba diving (SC), trawling (TR), in situ observation (OBS) or unknown (Unknown). Associations from papers in which multiple methods were used, but specific methods are known for each association are categorized under the known method. Many papers are comprised of multiple associations, as such, the “Individual” columns include each association separately, “Paper” columns report by paper.

Figure 5. Percent of sampling by depth.

The depths of samples with known depths. 68% of samplings had known depth data (pie chart). 74.4% of sampling was done above 30 m. Where depth ranges were given (i.e., 8 to 30 m) the deeper value was used.