Intertidal Fauna

Inter‐tidal fauna Hydroids Hydroids are the important inter‐tidal fauna of rocky shores and coral reefs. They play a vital role in many food chains, directly or indirectly. Various taxonomic and ecological studies have been performed throughout the world. Many researchers have made valuable contribution to the study of Indian hydroid fauna. But still a vast majority of hydroid fauna from Indian waters is unknown. At present, BNHS is studying Hydroids along Ratnagiri coast in Maharashtra and some parts of Gujarat. Some new records have been already published in the last two years from these areas. The study of systematic assessment and distribution of hydroids along with their relationship with other associated organisms has been undertaken. From the conservation point of view, these studies will be beneficial to save our rocky shores and coral reefs. Hydrozoa Owen, 1843, is a wide and heterogeneous group under Phylum Cnidaria. These aquatic animals are found primarily in marine ecosystems, but some fresh water species are also known. Hydroids are best known for their stinging property due to the presence of cnidocysts (stinging cells). There are around 3800 nominal species of hydroids present worldwide. Hydroids are complex animals to study and identify. Their complex life cycle includes two stages; sessile polyp and free swimming medusa. Polyps remain attached to the hard substratum and medusa swim freely until they settle. Different types of polyps have different functions. Gastrozooids are feeding polyps, gonozooids are reproductive in function, whereas dactylozooids are defensive polyps. Medusa is the sexually active stage. Hydroids are colonial, solitary or pelagic. The latter are often confused with jellyfishes. Most familiar pelagic examples of hydrozoans are Porpita porpita, Velella velella and Physalia physalisas. Obelia is polypoid and Hydraas is a freshwater genus. Class Hydrozoa is commonly divided into two sub‐classes; Hydroidolina and Trachylinae. These sub‐
classes are further divided into seven orders; viz. Anthothecata, Leptothecata, Limnomedusae Siphonophorae, Actinulidae, Narcomedusae and Trachymedusae. Hydroids’ symmetry is tetramerous, polymerous or exceptionally bi‐radial. Systematics of hydrozoans is highly complex. Diversity in life forms and life cycles has always created complexity in systematics studies. Now‐a‐days, molecular taxonomy and phylogeny are used to establish the relationship between them and to identify their trend in evolution. Hydrozoan taxonomy is still under revision. Physalia physalis Obelia geniculata Identification depends on general morphology of the hydroid colony. Appearance of the colony and colony forms are most important. Morphology of colony includes general polyp structure, colony structure, cnidocysts composition and reproductive bodies. Hydroids play a vital role in inter‐tidal faunal associations. They are important benthic and planktonic feeders. Some capture food with the help of their stinging tentacles, while some also feed on fish larvae. Many species of sea slugs are known to feed on hydroids. Some hydroids are used as a micro niche by various invertebrates such as caprelids, sea spiders and amphipods. Small hydroids use other showy hydroid colonies as their substrate. Various substrates of hydroids include common inter‐tidal flora and fauna such as algae, sponges, bryozoans, worm tubes and shells of molluscs. Sea slug Doto sp feeding on Hydroid Population studies of some fascinating host Cnidarians and their symbiont crustaceans The inter‐tidal zone in the coastal areas is considered to be a highly tolerant zone, as it witnesses constant changing water levels, in addition to high anthropogenic influence. Having said this, the region harbours the most diverse marine groups, which can be seen as the water recedes during the ebb tide, literally transforming the so‐called “still world”, into an altogether new marine kingdom, teeming with Life! The rock pools exhibit a three dimensional ecosystem, whereas the sandy beach and mudflat inhabitants exhibit their unique adaptability. This diversity and adaptability makes them a perfect topic for scientific study with areas like taxonomy, behavior and ecology yet to be fully explored. The inter‐tidal area of Marine National Park in Gujarat, one of the richest in marine biodiversity in the country, covers an area of 163 sq km and includes an archipelago of 42 islands. Out of these, the ongoing study of BNHS marine conservation programme focuses on two very prominent islands, viz. Poshitra and Narara. The inter‐tidal area of the former is a coral reef and is rocky, while that of the latter is dominated by rock and sand serving to be a perfect nutrient rich habitat for many marine invertebrates. One of the most fascinating creatures encountered here are the sea anemones of the family Stichodactylidae. For instance, the Haddon’s Carpet Anemone is found embedded in the sandy substratum of the shallow warm waters of the inter‐tidal area. Further observations reveal a surprising symbiotic relationship of the anemone with the beautiful Five‐spotted Shrimp Periclimenes brevicarpalis. The symbiont is found playing with the poisonous stinging tentacles of the host, quite enough to paralyze any other invertebrate intruder! Majority of the shrimps in the present study were found as singles or in pairs and in direct contact with the tentacles. The shrimp is known to find refuge in the host for protection and food and pays back the debt by keeping the host clean. The study focuses not only on the taxonomy, but also the on beautiful symbiotic relation they exhibit. Apart from covering the behavioral association of these two wonderful groups, BNHS study also deals with the population aspects, such as impact of host abundance on the community structure of shrimps and their con‐specific monogamity. Even though the area has been protected, it is prone to various anthropogenic threats and must be monitored from the conservation point of view. This study of symbiosis could be the first of its kind, known to have conducted in India. Expanding the geographical base, BNHS is now also working in the inter‐tidal areas of Andaman and Nicobar, where some surprising aspects of this symbiosis could be explored. Haddon’s Carpet Anemone exposed during ebb tide in Narara, Gujarat Shrimp Periclimenes brevicarpalis on its host, Haddons’ Carpet Anemone Stichodactyla haddoni Porifera Sponges are a group of porous, simple and sessile organisms mostly inhabiting the marine environment and exhibiting a wide variety in shapes and sizes. These are filter feeders possessing skeleton of spicules, which is an important feature in their systematics and taxonomy. Baseline surveys conducted by BNHS along the coasts of Maharashtra and Gujarat showed great diversity of the marine inter‐tidal sponges. These are well recorded historically from reef areas of Gulf of Kutch, Gujarat by various researchers, but rarely from Konkan in Maharashtra. For understanding the importance of sponges in the food chain, their medical value (bio‐active compounds) and the increasing environmental stresses on them; intensive studies for baseline data are necessary. This will enable the researchers to understand their present status as well as ecological importance. Phylum Porifera commonly known as sponges are pore bearing, simple, asymmetric and sessile organisms found in freshwater as well as in the marine environment. Approximately 9,000 species of sponges (Phylum Porifera) are marine inhabitants. They exhibit a wide variety of sizes and shapes and are distributed throughout the world from the poles to the tropics and found inhabiting shallow coastal waters to the great depths of the ocean. Sponges are filter feeders. They feed on plankton or organic material from water. Mineral spicules are the characteristic features of sponge skeletons and important in systematics and taxonomy of the same. Sponges can reproduce both sexually and asexually. Sponges are of different shapes and colours. Some colours warn for the potential toxicity or distastefulness. Recent research shows their ability to produce novel molecules for their defence, which has some bio‐medical value. Worldwide, large species of sponges belonging to class Demospongia are harvested for commercial use. In India most of the studies have been till now confined to Gulf of Mannar and Gulf of Kutch in Gujarat; Palk Bay in Tamil Nadu; Lakshadweep and Andaman & Nicobar Islands. So far only 40% of the sponge resources have been studied. According to Wildlife (Protection), 1972, sponges of class Calcarea are considered as Schedule‐III species (game species). This act provides protection to some of the species. A majority of the species commonly inhabiting the coastline are of class Demospongia. By keeping in mind the increasing environmental stress to the coastline and the lack of baseline data, it is necessary to study these areas intensively. Recently, BNHS initiated studies on sponges along Maharashtra coast as an extensive biodiversity documentation programme. Oceanapia saggitaria Neopetrosia sp. with visible oscules Haliclona sp. (Pale White) Haliclona sp. (Pink) Globular Ircinia fusca Encrusting Dysidea cf fragilis with sponge in network Haliclona sp. (Purple) Ball Sponge Cinachyra arabica Encrusting Chondrilla australiensis Sponge Spicules Polyclad Flatworms Polyclad flatworms live in the shallow depths of the sea except few species, which are found even at greater depths. They are fragile and brightly coloured worms. In systematics, Polyclads are a part of the free living group of the phylum Platyhelminthes, under the clade Rhabditophora. As the name suggests (Poly ‐ many, clade ‐ branches), highly branched intestines are a peculiar anatomical character of these worms. The polyclad worms first appeared in modern scientific literature in the late eighteenth century and further research continued on various aspects of their lifecycle in Europe and the Americas. However, Indo‐Pacific region was later come in to focused especially during Nineties and further. Several ecological aspects of these worms are currently being studied. Associations of polyclad with other littoral inhabitants like sponges, corals, barnacles, molluscs, bryozoans, ascidians, algae and sea grass have been found out, including some symbiotic relationships. Commensalism had also been recorded between few acotylean species and hermit crabs. Acotylean polyclad especially of the genus Stylochus predate on commercially important bivalves such as oysters and mussels. Thus, they are believed to have a disastrous impact on the aquaculture industry, as has been recorded at various places around the world. Some of these worms are also found feeding on giant clams, corals and ascidians and apparent specificity has been recorded for few species. The most conspicuous Cotyleans exhibit diverse colour and these colour patterns are attributed to their aposematism. Besides, their cryptic nature, mimicry of opisthobranch molluscs and fishes is one of their defensive mechanisms or adaptations to cope up with surrounding environment. Additionally, toxic chemicals like Tetrodotoxin and Staurosporin or at least their derivatives in the tissues, have also been recorded. The interesting aspects in studying inter‐tidal community ecology include understanding the distribution pattern of species along the habitat types, interactions between species and the surrounding environment and relative adaptation strategies. Seascape features of the western coast of India, in the state of Maharashtra, where BNHS is presently working on these species, are dominated by vast inter‐
tidal areas. They comprise of eroded rocky cliffs and wave cut platforms of inter‐tidal areas which include pebbles, cobbles, boulders, shallows, few metres deep rock pools and patchy coral reef beds, which are the favored habitats of many cryptic marine invertebrates. Although diversity exists within these habitat types and the associated floral and faunal structures, available literature or documentation is patchy and focuses on few organisms and certain regions of this coastal area. Taxonomy based study is a prerequisite in diversity analysis of any region. Initiatives by BNHS involve the preliminary surveys for documenting biodiversity and creating baseline data for this neglected group of worms. Objectives of the study involve documentation of polyclad diversity with respect to specific habitat types. Efforts will also be made to collect data for certain ecological aspects such as food preference. Inter‐tidal region comprising the rocky shores in Ratnagiri District, Maharashtra Thysanozoon sp Study of Bryozoan taxonomy along the Konkan coast Ratnagiri District along the Konkan coast of Maharashtra has one of the most diverse inter‐tidal regions of the country. These areas with their well dispersed and abundant rock pools are ideal for the study of inter‐tidal diversity as they are one of very few remaining pristine patches of the shoreline. Conservation of these areas depends on them being thoroughly studied and understood. Of the many groups of invertebrates found and studied by BNHS, the highly diverse bryozoans are a significant group. A detailed study on the taxonomy of the group from this area can add substantially to the present knowledge at the level of single taxa as well as the overall inter‐tidal ecosystem. The rocky inter‐tidal zone is one of the most dynamic areas to study and the life forms it hosts are equally resistant and accommodating to the ever fluctuating surrounding environment. The littoral area of Ratnagiri District in Maharashtra is one such area with well dispersed rocky and sandy shores. These pristine shores are apt for the study of life in the inter‐tidal zone and more so for taxonomist studies of various groups of invertebrates inhabiting these areas and their life cycles. One such group is that of the Bryozoans whose study has been undertaken by BNHS as a part of its inter‐tidal diversity project. The phylum Bryozoa is a diverse group of colonial invertebrates found ranging from the inter‐tidal zone to the abyssal depths of the ocean. An exceptional diversity is seen in their forms and shapes. Being encrusting, erect, coralline, fenestrate and winding, they at times pose a striking resemblance to other groups such as algae, hyroids, colonial ascidians and even corals! Furthermore these animals can also be called as the foundation group as they make it possible for other invertebrate groups to thrive and propagate in these harsh environments. They have been observed to be working in close association with a number of plant and animal forms of the littoral zone. Electra indica has been observed encrusting a species of Sargassam. Certain gastropod species have been observed laying their egg cases on colonies of select cheilostome bryozoans. Amphipods are commonly seen occupying spaces in the empty individual zooids. The complex external skeleton and the micro size make bryozoans a challenging group to study but in order to understand the ecology of the inter‐tidal zone, it is imperative to study these life forms. BNHS is undertaking regular surveys at select sites along the Ratnagiri coast to comprehend the diversity of bryozoans, to study their variability across seasons, their inter‐relations with other groups and eventually to conserve them. A Cheilostome (Smittinidae) bryozoan colony Electra indica encrusting Sargassam sp