Life Cycle and Life History Strategies of Parasitic Crustacea

Abstract

Different parasitic life strategies are described including four new life cycles: complex rebrooding, micro-male, mesoparasite and prey-predator transfer. Four new life cycle behaviours are named: nursery hiding, mid-moult stage, positive precursor (intraspecific antagonism) and negative precursor (ambush strategy). Further strategies discussed are opossum attack, double parasitism (doubling of the normal reproductive set), duplex arrangement (separated male-female pairs), simple rebrooding, and describing how displaced parasites and superinfections may partly elucidate life cycles. Proportional stunting masks life history effects of parasitism; cuckoo copepods are true parasites and not just associates; burrowing barnacles (acrothoracicans) are not parasites. Further findings based on life cycle information: branchiurans and pentastomes are possibly not related; firefly seed shrimp are not parasites; copepod pre-adult life cycle stages are common in the western pacific but rare in Caribbean; harpacticoids on vertebrates are not parasites; cuckoo copepods are true parasites; explained the importance of pennellid intermediate hosts. Crustacean parasite life cycles are largely unknown (1% of species). Most crustacean life cycles represent minor modifications from the ancestral freeliving mode. Crustacean parasites have less complex and less modified life cycles than other major parasite groups. This limits their exploitation of, and effectiveness, in parasitism. However, these life cycles will be an advantage in Global Change. Most metazoan parasites will be eliminated while crustaceans (and nematodes) will inherit the new world of parasites.

Exceptionally preserved cryptoniscium larvae - morphological details of rare isopod crustaceans from French Cretaceous Vendean amber

“…Isopoda (woodlice and their relatives) is an enormously diverse group of malacostracan crustaceans. Having a marine origin, isopod species did not only master the transition to a fully terrestrial life (Oniscidea), they also inhabit deep sea and freshwater environments, and some groups even developed parasitic lifestyles (Williams and Bunkley-Williams, 2019). Some isopod species have been known as parasites of fishes and crustaceans for a long time (e.g., Müller, 1862).…”

First record of the snapper-choking isopodCymothoa excisa(Isopoda: Cymothoidae) parasitizing invasive lionfishPterois volitans(Scorpaeniformes: Scorpaenidae)

“…In this case, neither specimen in Alacranes Reef appeared to be attached to the tongue or feeding on the lionfish host. Williams & Bunkley-Williams (in press) described juvenile prey-predator transfers as a new life cycle strategy in Cymothoa oestrum . This latter transfer was previously documented in adult Anilocra acuta to King Mackerel Scomberomorus cavalla (Williams & Bunkley-Williams, 1994).…”

Habitat and host associations of the fish‐burrowing parasite Artystone minima (Cymothoidae: Isopoda) in eastern Amazonia

“…Although both were collected from the backwater bay where many N. beckfordi are parasitized by A. minima, the lack of parasitism in Nannostomus eques Steindachner, 1876 and Nannostomus trifasciatus Steindachner, 1876 may be a result of their differential habitat use (spatial use of the water column) or because they were found in lower abundances in habitat 5 throughout the year (Table S2). Cymothoid mancae have been described as phototropic in the marine environment (Williams & Bunkley‐Williams, 2019), but freshwater cymothoid mancae present alternative strategies including waiting upside‐down on the substrate (Thatcher, 2000). Movement of N. eques is restricted to vegetation near the surface and therefore may not be subjected to settlement of parasite mancae at lower depths.…”

“…Males develop female gonads after successful infestation of a host but only when it is unoccupied by another female. Suppression of sex-change of newly arrived males by preexisting females is regulated by a complex process of chemical cues (Williams & Bunkley-Williams, 2019). Cymothoids typically exhibit low infestation rates, with a single adult pair parasitizing the same host individual, and, possibly because they compete for the same host resource, there is strong sexual dimorphism with large, embryo-and larvae-incubating, females, and smaller males (Thatcher, 2000;Williams & Bunkley- Williams, 2019).…”

“…In their infectious stage "mancae," as well-developed larvae are known, can survive for several days without finding a host, and have large eyes and long setae on their pleopods (swimming-appendages) that aid swimming dispersal to new host individuals (Araújo, 2008;Costa & Chellappa, 2010;Sartor, 1987;Thatcher, 2000;Williams & Bunkley- Williams, 2019). However, setae are molted by adults, and eyes are generally reduced, limiting the ability to locate other host individuals in the event of being dislodged.…”