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According to Paracer a symbiosis is the “association between two or more different species of organisms”. Plant and animal associations, similar to all symbiotic relationships, vary in the degree that each symbiont benefits from the interaction. Most commonly the plant is in search of a symbiont that will aid in the plant’s reproduction and dispersal of offspring, protection from predators as well as an environment that provides the most favorable conditions for growth. Animals on the other hand may receive essential nutrients or in the case of specific insects a safe location to reproduce. Plant and animal associations are not limited to only those that occur on land. Many aquatic plants also benefit from relationships with animals that thrive in similar environmental conditions. Many questions should be considered when studying plant and animal symbioses. For example does geographic location affect the strength of the symbiosis/ does the specific symbiosis even exist in different geographies? Does the relationship protect against one organism “cheating”? Is the symbiosis obligative or facultative? Are there other organisms involved in relationship other than the two main contributors?

Terrestrial Plant-Animal Associations:
Fig-Wasp Symbiosis
Brazil Nut Tree - Animal Symbiosis
Yucca Plant-Moth Symbiosis

Aquatic Plant-Animal Associations:
Coral-Virus Symbiosis
Sponges and Cyanobacteria

Coral--Algal Symbiosis

Coral and Algae are necessary for the maintenance of the coral reef. What we typically call “coral” is actually a combination of coral and its algal symbiont. The coral receives carbon sources and energy from the algae while providing the algae with protection and a place to live. The disturbance of this relationship by factors such as increasing ocean acidity and global climate change stress the coral and result in the expulsion of algae. The loss of algae results in coral bleaching which has become a major concern to marine scientists and researchers. When the algal population of a coral reef declines the coral begins to die and the diversity of the coral and the surrounding habitat decreases. Coral is a food source and home to many marine organisms other than algae so when the coral dies animals that consume the coral as well as animals that consume them also die. Recent studies hope to discover ways to increase coral resiliency to environmental changes by revealing symbioses with thermal tolerant algae.

Other papers discussing this relationship:
Little on Algal endosymbionts
Goulet - Most Corals May Not Change Their Symbionts

Want to learn more about coral, algae, and the significance of their relationship?

Sea Slug--Algal Symbiosis


Algae is quite resourceful. It presents itself as food for smaller organisms, and photosynthesizes, providing other species with oxygen. The sea slug Elysia timida is just one of many species that have a symbiotic relationship with algal. Elysia timida particularly sequestered chloroplasts from algae for personal advantage to keep the plastids. The used a deep-sequencing approach to focus on expressed genes from photosynthesizing animals, in order to identify expressed genes that might have been acquired from algae. The sea slug and algae symbiotic associations are one of many relationships that benefits from that algae component. So what can we assume about the algal and Elysia timida? Because the studied (the link provided below) was able acquired the following conclusions:
1) acquired algal photosynthesis genes, germ line or otherwise
2) sequestered algal photosynthesis genes
3) sequestered algal photosynthesis mRNAs
All three cases expressed algal nuclear genes specific to plastid photosynthetic functions should have appeared among the expressed sequence tag (EST) sequences.
These results stand in marked contrast to recent reports of gene transfer in a different sacoglossan species with long- term plastid maintenance! Rumpho et al. (2008) reported that the nuclear-encoded psbO gene of the xanthophyte V. litorea had been transferred from the algal to the E. chlorotica genome and is functionally expressed there. But, the targeting of this gene product to the plastid entails considerable difficulties because of the different number of membranes surrounding V. litorea plastids in the alga and in the slug (V. litorea plastids: surrounded by four membranes in the alga, the outermost two of those membranes are digested during kleptoplasty in the slug) So, if psbO has been transferred in E. chlorotica, how does the protein get inside the kleptoplast and maintain for extended period of time?

Additional Information on Solar Powered Sea Slugs