Vol. 62, 2023
Understanding the Symbiotic Relationship between the Sea Urchin Loxechinus albus (Molina, 1782) and the Pea Crab Pinnaxodes chilensis (H. Milne Edwards, 1837): a Potential Parasitism
Hans N. Jaramillo1, Luis P. Salas-Yanquin1, Joseline A. Büchner-Miranda1, Víctor M. Cubillos1, Jaime A. Montory2, Jan A. Pechenik3, Luis M. Pardo1, and Oscar R. Chaparro1,*
Austral de Chile, Instituto de Ciencias Marinas y Limnológicas,
Valdivia, Chile. *Correspondence: E-mail: firstname.lastname@example.org (Chaparro).
E-mail: email@example.com (Jaramillo); firstname.lastname@example.org
(Salas-Yanquin); email@example.com (Büchner-Miranda);
firstname.lastname@example.org (Cubillos); email@example.com (Pardo)
2Universidad de Los Lagos, Centro i~mar, Camino a Chinquihue km 6, Puerto Montt, Chile. E-mail: firstname.lastname@example.org (Montory)
3Biology Department, Tufts University, Medford, MA 02155, USA. E-mail: Jan.Pechenik@tufts.edu (Pechenik)
(Received 1 July 2022 / Accepted 27 January 2023 / Published -- 2023)
Communicated by James D. Reimer
The echinoderm Loxechinus albus has a symbiotic relationship with the pinnotherid crustacean Pinnaxodes chilensis.
Females of the crustacean develop in the terminal section of the sea
urchin’s digestive system, remaining there for life. This relationship
has been suggested as commensalism. However, a potential negative
impact on gonadal development and on the morphology of the sea urchin’s
digestive system suggest that it is instead parasitic. To study if
there is a negative impact of the crustacean symbiont on the host,
specimens of L. albus of all
sizes were collected from a rocky shore from southern Chile. The
gonadal and somatic tissues of sea urchins that were and were not
harboring the pinnotherid were weighed and compared. Our results show
that the presence of the pinnotherid was related to sea urchin gonads
of lower biomass, decreased gonadosomatic index levels, and alterations
in the morphology of the terminal portion of the host digestive system.
The lower gonadal biomass suggests a negative impact on gamete
production as well as a diversion of energy due to changes of the
digestive system tissues and the potential consumption of algal food by
the resident crustacean. These results suggest that the prolonged
relationship between these two species is one of parasitism rather than
one of commensalism.
Key words: Parasitism, Symbiosis, Sea urchins, Pinnotherid, Crustacean.
Jaramillo HN, Salas-Yanquin LP, Büchner-Miranda JA, Cubillos VM,
Montory JA, Pechenik JA, Pardo LM, Chaparro OR. 2023. Understanding the
symbiotic relationship between the sea urchin Loxechinus albus (Molina, 1782) and the pea crab Pinnaxodes chilensis (H. Milne Edwards, 1837): a potential parasitism. Zool Stud 62:18.
materials: Fig. S1丨Fig. S2丨Fig. S3