Locomotion of Anthocyathus Mushroom Corals (Scleractinia: Fungiidae) of Andaman and Nicobar Islands, India

Indian Journal of Geo-Marine Sciences Vol. 44(6), June 2015, pp. 818-824

Locomotion of anthocyathus mushroom corals (Scleractinia: Fungiidae) of Andaman and Nicobar Islands, India

Tamal Mondal* & C. Raghunathan

Zoological Survey of India, Andaman and Nicobar Regional Centre, National Coral Reef Research Institute, Haddo, Port Blair-744 102, Andaman and Nicobar Islands, India [E-mail: [email protected]]

Received 5 February 2014; revised 11 September 2014

Present experimental work carried out on three species of free-living, solitary mushroom corals such as Fungia paumotensis Stutchbury, 1833, Fungia repanda Dana, 1846 and Ctenactis echinata (Pallas, 1766) to compare their mobility pattern and active influencers for this activity. Smooth under-surfaced mushroom coral with granular costae move faster than echinose type of costae as this resistor against the mobility by gripping of anchorage with the bottom surface. The elongated and oval shaped structure reduces the friction against the bottom surface and expedites migration. Individuals with flat morphology tolerate higher degree of water pressure in comparison with the oval shaped animal and reduce the locomotion rate as a result of higher friction by touching entire costal surface with the bottom.

[Key words: Anthocaulus, free-living, solitary, Fungiidae, Andaman and Nicobar Islands]

Introduction taken place with the help of the fungiid by serving Corals are generally known as sedentary as nuclei for the establishment of new reefs11. biological creatures but in case of Fungiids corals Corals under the genus Fungia has the capability that is quite different. Free-living corals of the to coexist with colonial species in the reef family Fungiidae are common on coral reefs environment. These corals appear to survive throughout much of the tropical Indo-Pacific1. The storm-generated abrasion better than do co- basic requirement of the scleractinian life cycle occurring colonial corals12. Active locomotion can depicts that it need a solid substratum for the be seen among the unattached Fungiidea species13. settlement of the planula larvae. Due course of The ability of movement helps them to avoid development, all the mushroom corals start with overgrowth4. Several species of this family the state of attachment with a substratum and accomplish this through the bouts of rocking retain the attachment up to juvenile form but most motion created by periodic expansion and of them detached at next stage of life cycle and contraction of the coelenteron9, 14, while others are identified as free living form. After the break off righted passively due to the hydraulic response of from attached life, they reproduce asexually to their skeletons12. Behavioural pattern plays a form unconnected free-living polyps1. Most of the major role for righting responses among the mushroom corals i.e. Fungiidae are well mushroom corals15. Polyp behaviour also appears developed with the mobile activity during the free responsible for coral migration. Fungiids employ living stage of life2, 3. Mobility helps to diverse mechanisms of benthic mobility, including concentrate an alternate life history strategy for controlled constriction and relaxation of distended the corals and help to exert unique impacts on reef tissue15-17, the use of long, continuously-expanded community structure. Free-living corals may tentacles as a ship-sail to facilitate transport by retreat from competitive contact with large currents13, and discharge of mucus float to amplify colonial corals4, 5 and try to avoid bleaching by buoyancy during locomotion (Hubbard 1972). migrating down slope6. They risk burial due to This present paper implies the mobility pattern of migration onto soft substratum7-9 and may be three species of mushroom corals such as Fungia overturned by water motion and bioturbation10. paumotensis Stutchbury, 1833, Fungia repanda Mobility of mushroom corals extend themselves Dana, 1846 and Ctenactis echinata (Pallas, 1766). to a new areas where establishment of reef can be MONDAL & RAGHUNATHAN: LOCOMOTION OF ANTHOCYATHUS MUSHROOM CORALS 819

Material and Methods were selected in three depth zones. First one was The experimental study was carried out near on flat at the depth of 2 m, second one was on Pongibalu Jetty (Lat.11°30.956’N and slope at the depth of 9 m and the third one was on Long.092°39.206’E) at South Andaman (Fig. 1) 15 m at base. All the selected three species of which is located on the boundary line of Mahatma mushroom corals were commonly distributed in Gandhi Marine National Park (MGMNP). Wave the experimental study area. Shallow flat and action in the study area is very minimal or nil strongly inclined slope contains large patches of throughout the year. This reef area harbours diversified coral coverage. Basal part of the area diversified scleractinian corals and their associated shows a gradually declining bottom with few faunal communities. Depth of the study site is in patches of coral reefs. One quadrate of 1 m2 (made between 0.6 m and 15 m, has the tidal amplitude up of PVC pipe) was placed on the top of the 4 near about 2 m. Sea substratum in the study area iron made strand at each of three depth area. Each is rocky coupled with live and dead corals. The of the quadrates were divided in to 25 sub- study area is formed with continuous reefs to the quadrates of 20cm2 area to collect the accurate depth of 12 m and beyond that some patches of data of their dispersal from one place to another as reef could be seen on the study substratum at the well as direction. Each of the experimental plots depth of 13 m. However the percentage of rubble was marked by a buoy tied to the solid boulder or is fairly good at the depth of 7 to 10 m. reefs. Four specimens for the species Fungia paumotensis Stutchbury, 1833, while two specimens each for Fungia repanda Dana, 1846 and Ctenactis echinata (Pallas, 1766) were placed in each of the quadrate. The placed location of each of the sample was marked to measure their

Fig. 1: Study area- Pongibalu

Three species of fungiids viz. Fungia paumotensis Stutchbury, 1833, Fungia repanda Dana, 1846 and Ctenactis echinata (Pallas, 1766) Fig. 2: Experimental plots and substratum structure were selected to carry out the in situ observation at the three experimental plots. All the three species monthly movement. All the samples were marked differs in their basic morphology such as shape, with individual tag and tied tightly around each size and structural attributes or ornamentation of corals. All the samples were measured using under surface or costae. The experimental plots verniar calipers (Aerospace, 074 15376) and

820 INDIAN J MAR SCI VOL 44, No.6, JUNE 2015 centimeter scale according to their Eight individuals of mushroom corals for each of length, width, diameter (for circular sample) three species were placed in each experimental height as well as weight. Data on these parameters plot at 2m, 9m and 15m depth (Fig. 2). The were noted before placing the specimens in each characteristics of the sea bottom at the experimental plot (Fig. 2). experimental plot areas are given in Table 1. The experimental studies were carried out for Vertical transparency of water column was 7- 9m 12 months from December 2011 to November at the study area during the experimental period. 2012 to record the nature and distance of mobility All the experimental animals are different in among the three species of fungiid corals. Data on their shape, size and weight which are the direction and the distance travelled by the corals regulatory agents behind the locomotary and their position (upright and inverted) were behaviour. Morphometric measurements of the collected on monthly basis by employing SCUBA experimental animals were depicted in tabular diving in the study site. Undersea photographs form to understand their static inter and intra- were taken by a digital camera (Sony Cyber Shot, species differentiation (Table 2, 3 and 4). DSC-T900, 12.1 megapixels, marine pack). Costae are one of the prime controlling agents Temperature of water and atmosphere was for locomotion of fungiids. In order to observe the recorded with the help of handheld mercury role of costal structure, three species with varied thermometer and transparency of water column costal configuration were used for the study. The was measured by Sechhi disc. costal structures of the selected corals are Results described in Table 5.

Table 1: Substratum structure of experimental plots Reef zone Reef flat Reef slope Reef base Depth (m) 2 9 15 Substratum Hard rocks and rubbles Rubbles and sand Muddy sand and few rubbles

Table 2: Morphometric measurements of specimens in the experimental plot at 2m depth Length Width Height No. of Sample No. Species (cm) (cm) (cm) Weight (gm) Mouth Shape Q1/M/S1 Fungia paumotensis 11.6 7.7 2.1 250 1 Elongated Q1/M/S2 Fungia paumotensis 10.2 6.9 2.3 230 1 Elongated Q1/M/S3 Fungia paumotensis 10.1 6.9 2.1 200 1 Elongated Q1/M/S4 Fungia paumotensis 10.6 7.5 2.3 250 1 Elongated Q1/M/S5 Ctenactis echinata 13.4 6.9 2.7 220 1 Elongated Q1/M/S6 Ctenactis echinata 24.8 9.6 3.1 850 1 Elongated Q1/M/S7 Fungia repanda 10.9 - 3.1 250 1 Circular Q1/M/S8 Fungia repanda 9.7 - 2.7 170 1 Circular Table 3: Morphometric measurements of specimens in the experimental plot at 9m depth Length Width Height Weight No. of Sample No. Species (cm) (cm) (cm) (gm) Mouth Shape Q2/M/S1 Fungia paumotensis 10.6 7.4 2.3 200 1 Elongated Q2/M/S2 Fungia paumotensis 13.3 7.8 2.5 400 1 Elongated Q2/M/S3 Fungia paumotensis 13.1 9.3 2.4 450 1 Elongated Q2/M/S4 Fungia paumotensis 14.6 9.2 4.8 525 1 Elongated Q2/M/S5 Ctenactis echinata 24.1 11.6 4.1 950 1 Elongated Q2/M/S6 Ctenactis echinata 19.8 8.9 2.5 490 1 Elongated Q2/M/S7 Fungia repanda 9.6 - 2.3 240 1 Circular Q2/M/S8 Fungia repanda 11.6 - 2.1 300 1 Circular Table 4: Morphometric measurements of specimens in the experimental plot at 15m depth Length Width Height No. of Sample No. Species (cm) (cm) (cm) Weight (gm) Mouth Shape Q3/M/S1 Fungia paumotensis 12.5 9.2 2.9 350 1 Elongated Q3/M/S2 Fungia paumotensis 11.7 8.6 2.3 260 1 Elongated Q3/M/S3 Fungia paumotensis 11.1 7.3 2.4 260 1 Elongated MONDAL & RAGHUNATHAN: LOCOMOTION OF ANTHOCYATHUS MUSHROOM CORALS 821

Q3/M/S4 Fungia paumotensis 9.6 8.4 2.6 240 1 Elongated Q3/M/S5 Ctenactis echinata 29.1 12.9 2.5 2000 1 Elongated Q3/M/S6 Ctenactis echinata 13.4 6.8 2.1 170 1 Elongated Q3/M/S7 Fungia repanda 8 - 1.6 110 1 Circular Q3/M/S8 Fungia repanda 10.2 - 1.7 200 1 Circular

Table 5: Comparative costal structures of three species Fungia paumotensis Ctenactis echinata Fungia repanda  Well developed, equal or sub-  The costae are unequal in size.  Perforated lower surface. equal, laminar costae towards  They are more or less straight  Numerous cyclically unequal the periphery. and distinct. costae.  They are gradually replaced by  Coarsely ornamented with  Most costae are low ridges. rows of laterally compressed spines, vary from long and  Costae are covered with lobes after those cylindrical, echinose to short and coarsely numerous blunt, granulose blunt spines, which become granulated. spines, club-shaped or irregular. branching.  Perforations are visible on the outer part of the undersurface. All the corals were placed in experimental quadrates i.e. at the depth of 2 m, 9 m and 15 m in reef flat, slope and base showed a distinct differentiation in terms of mobility. Corals at the reef flats showed a higher degree of mobility 18 Fungia paumotensis than the other two zones. Corals are with 16 Cteanactis echinata Fungia repanda

heavier weight and coarsely arranged costae i.e. 14 Ctenactis echinata showed lower rate (87cm) of 12 movement than the light weight Fungia 10 paumotensis and Fungia repanda. In reef flat, 8 6 Distance (cm) Distance Fungia repanda showed the maximum (207 cm) 4 mobility with its light weight and circular 2 structure than the other two species (Fig. 3). In 0 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov reef slope and base, the elongated Fungia Year : 2011 to 2012 paumotensis travelled a comparative long Fungia paumotensis distance than other two species (Figs. 4 and 5). 18 Cteanactis echinata The elongated and coarsely ornamented 16 Fungia repanda specimens can migrate lower distance in 14 comparison with other species with blunt, 12 laminar, granulose spines. Structural 10 confirmations with such above said under 8

surface give the advantages adaptability to the (cm) Distance 6 Fungia paumotensis and Fungia repanda to 4 Fig. 4: move for a long distances. 2 0 Fungia paumotensis Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 35 Cteanactis echinata Year : 2011 to 2012 30 Fungia repanda Monthly locomotion

25 at 9m depth 20 15

Distance (cm) Distance 10 5 0 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Year : 2011 to 2012 Fig.5 Monthly locomotion at 15m depth

Fig. 3: Monthly locomotion at 2m depth

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Intra species studies showed that variation Scrutiny of the results revealed that encountered in a particular species depending on maximum migration was observed in the the depth of experimental plots. Locomotion of months of December 2011 to February 2012 for Fungia paumotensis was maximum of all the three species whereas the minimum was 138.38cm during 12 months at the depth of 15m found mostly in the month of March 2012. All (Fig. 6). Ctenactis echinata travelled a total of the corals remained upright (oral side up) during 127.22cm at the depth of 2m which is higher the study period of one year. than the same species at the depth of 9m and In general, the movement of the fungiid coral 15m (Fig. 7). Fungia repanda moved to the Fungia paumotensis showed similar values of maximum distance of 229.25 cm at the depth of distance at all three depths. Whereas, the 2m whereas the movements at other two plots distance moved by Ctenatis echinata decreased were drastically lowered (Fig. 8). in accordance with the greater depth. The 2m Depth 9m Depth 15m Depth Fungia repanda did not show any definite trend 18 of movement at all depths (Fig. 9). 16 14 Fungia paumotensis Cteanactis echinata 12 Fungia repanda 10 229.25 8 6 Distance (cm) Distance 4 2 138.38 0 128.29127.22 119.08 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 109.97 Year : 2011 to 2012 87.28 85.06 57.54 Fig. 6: Monthly locomotion of F. paumotensis

14 2m Depth 9m Depth 15m Depth 2m 9m 15m 12 Fig. 9: Comparative annual movement of fungiid corals at 10 different depth 8 Variation of locomotion was seen among the 6 three species of corals depending on the depth. The coral species Ctenactis echinata (R² = Distance (cm) Distance 4 0.921) and Fungia repanda (R² = 0.761) showed 2 negative correlation with the increasing depth. 0 Locomotion of those two species slow down Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov gradually in comparison with depth, whereas Year : 2011 to 2012 positive correlation was observed for the species Fungia paumotensis Fig. 7: Monthly locomotion of C. echinata (R² = 0.273) with the increased depth (Fig. 10).

250 Fungia paumotensis 2m Depth 9m Depth 15m Depth Cteanactis echinata

35 Fungia repanda 30 200 25

Distance (cm) Distance 150 20 15

Locomotion 100 10

5 50 0 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Year : 2011 to 2012 0 0 0.5 1 1.5 2 2.5 3 3.5 Depth: 1= 2 m; 2= 9 m; 4= 15 m

Fig. 8: Monthly locomotion of F. repanda y = 5.045x + 118.49 y = -72.095x + 278.05 y = -34.84x + 167.92 R² = 0.2731 R² = 0.7615 R² = 0.9217 MONDAL & RAGHUNATHAN: LOCOMOTION OF ANTHOCYATHUS MUSHROOM CORALS 823

position, no such physiological adverse effects Fig. 10: Correlation of annual movement of fungiid corals on their activity could be noted. Variation in at different depth environmental patterns also regulates the Discussion movement of organism20. Soft substratum can Fungiidae is the only family under the order be found in the reef base. In the present study, scleractinian exhibit the locomotion. Most one mushroom coral with smooth undersurface species under the family fungiidae possess a i.e. Fungia paumotensis move faster than that of free-living adult stage in their life cycle after the 18 other two species. Ctenactis echinata is with detachment from a stalk . Migratory behaviour echinose type of costal structure which acts as is one of the variable features among the resistor against the mobility by gripping of species. Coverage of distances can be measured anchorage with the bottom surface. by the mobility of the corals, but it depends on Morphological structure or size of the free living the undersurface. Corals can reach a long fungiids plays a role on the dispersal of them19, distance if the undersurface of the coral is 21, 22. Specimens with larger structure cannot smooth. Rate of movement of smooth move due to death of tissues on their costal undersurface corals will be higher than the areas. This immobility can be encounter as sank corals with costal spines. Spines will create 11, 19, 23 15, 10 specimen into the substratum . The resistance against the movement . Fungiids secretion of thick mucus sheath helps the are potential enough to move for a long 5 10 fungiids against damage . distance. According Hoeksema , Fungiids can The experimental animals did not showcase move up to 10m within a period of six months. any damaged tissue in their skeleton structure With the present experiment, it was found that during the study period. The replica animals of movement activity is an intrinsic property of the species Ctenactis echinata, considered for those fungiids and showed locomotion by experiments, are large in size with echinose covering around 2.5m distance with a period of ornamentation in ventral side. As the specimens one year. It was also seen that species with gradually show reduction in migration distance smooth undersurface, move greater distance in depending upon the depth, it can be said that the comparison with the species with coarse size and depth are inversely proportional or undersurface. negatively correlated with the movement. Other There are a number of abiotic factors such as two experimental animals viz. Fungia bottom relief, bottom inclination, and paumotensis and Fungia repanda, possess to substratum type and water turbulence take some extent equal arrangement of costal active part to influence the migration. Wave structure. But Fungia paumotensis show a actions have the potentiality to sweep away 10 gradually increased movement with the depth as shallow water corals from reef flats . On the the specimen is elongated and oval shaped other side the bottom substratum take part for which can reduce the friction level with the sliding down corals from its original position to bottom surface and helped the specimens to the other. Weight of any animal plays a lower move for a certain distance. Though the ventral role to make resistance against the sliding surface of the Fungia repanda is closely related activity. Corals support a variety of organisms to other species under same genus, but it showed which are called as coral associates which gradual reduction in distance moved with the include great number of faunal communities. increasing depth. It can be concluded that Among those, many animals show foraging Fungia repanda have to tolerate more water activity. This activity sometimes can be seen as 20 pressure than other species as they are the movement of corals . Wave action can morphologically flat individual, and the entire invert the corals from their proper position in costae will be in touched state with the surface lesser depth but in greater that can be performed 10, bottom. The friction between costae and bottom by fishes, lobsters, sea cucumbers, crabs etc. 12 surface can be seen in the form lowering . During the experimental period none of the migratory distance with the depth. With the sample was observed in inverted position, so it present experiments it can be said that, can be said that there was no influence or unattached fungiids have the mobility which are involvement of other animals for the migratory actively dependent on physical characteristics of activity. Inversion may create problem by bottom surface, depth, morphological structure blocking the mouth of fungiids which in turn (shape, size, dorsal and ventral surface) and affects a smooth physiological state. As the weight of animals. experimental specimens were in their proper

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