Life History & Behaviour

Feeding:

Montipora digitata has two main methods of gaining nutrients. The first method is through carnivorous feeding. The coral waits until a prey item comes into contact with their tentacles. Then the nematocysts, spirocysts and mucus on the tentacles all help to capture and immobilise the prey. Small prey such as plankton is carried via cilia on the tentacles to the mouth. Prey is swallowed through the pharynx into the coelenteron. Here extracellular digestion takes place.

The second method is via the zooxanthellae in the coral photosynthesising. Zooxanthellae are algal endosymbionts who have formed an obligate symbiosis with corals. M. digitata has been found to transmit their endosymbionts directly into their eggs rather than the species having to find their own zooxanthellae from the surrounding environment (Van Oppen et al 2004). Scleractinians can receive up to 50% of their energy needs from zooxanthellae (Ruppert et al 2004).

Reproduction:

Montipora Digitata can reproduce asexually and sexually. This species has a relatively short period of growth and mass reproduction before it dies (Heyward and Collins 1985). M. digitata has an ability to survive when damaged. This indicates that this species can
regenerate fast. M. digitata does this by asexually reproducing via fragmentation (Harpeni and David 2011). Fragmentation is when a part of the coral breaks off and forms its own colony (Ruppert et al 2004). This is M. digitata’s primary form of reproduction (Harpeni and David 2011). M. digitata can also reproduce sexually as they are considered a simultaneous hermaphrodite (Harpeni and David 2011). Mass spawning occurs twice a year when M. digitata releases egg-sperm bundles (Coll et all 1994). Mass spawning is when individuals of a species release sperm and eggs into the water column at a certain time. The sperm and egg combine to form a gamete, which then finds a place to settle and grow into a coral (Ruppert et al 2004). 

M.digitata can be found in attached and un-attached colonies. According to Harpeni and David 2011, this can affect the corals mode of reproduction. Un-attached colonies can produce many fragments and reproduce asexually (Harpeni and David 2011). Attached corals are considered to be more stable colonies and most likely use sexual reproduction in the form of mass spawning (Harpeni and David2011).  

Movement:

M. digitata is a benthic species, however it does have a pelagic stage in its reproductive cycle. During mass spawning, the eggs and sperm are released into the water column. Once they form a gamete, they ‘search’ or ‘swim’ with the use of flagella until they find the right place to settle and metamorphose into an adult form. Settlement is affected by factors such as temperature, water chemistry and substrate type.  

Respiration:

In Anthozoans, respiration occurs via diffusion across the body and the tentacles. This gas exchange is achieved through the ciliary flow of fluid over the gastrodermis and epidermis (Ruppert et al 2004).