Biology and Culture of Portunid Crabs of World Seas

Ramasamy Santhanam

• Publisher: Apple Academic Press
• Year: 2018
• Topic: Biological Sciences
• eBook ISBN:
  9781351795142
• Subtopic: Marine Biology
• Index: Biological Sciences

Biology and Culture of Portunid Crabs of World Seas provides an abundance of valuable first-hand information about the diversity, biology, ecology culture of the portunid crabs of the word seas.

Marine crabs play an important role directly or indirectly in the livelihood of millions of people around the world. They have been reported to make up about 20% of all marine crustaceans caught, farmed, and consumed worldwide. Among these marine crabs, portunid crabs or swimming crabs of the family Portunidae (Class: Crustacea; Order: Decapoda; Infraorder: Brachyura) assume greater significance in the marine industry owing to their delicate meat with nutritional qualities. Although, several species of portunid crabs are edible and commercially important, only a few species of Scylla and Portunus have been widely cultivated. This is largely due to the lack of information on the biology of portunid crabs. Keeping this in view, this new volume presents the biology and aquaculture of marine portunid crabs.

This volume will be of great use for researchers and students of disciplines such as fisheries science, marine biology, aquatic biology and fisheries and zoology and will also serve as a standard reference for college, university, and research libraries around the world.

CHAPTER 1

INTRODUCTION

CONTENTS

1.1 Portunid Crabs

1.2 Subfamilies and Genera of Portunid Crabs

1.3 Commercially Important Portunid Crabs

1.4 Role of Portunid Crabs in Aquaculture

1.5 Nutritional Values of Portunid Crabmeat

1.6 Potential Value of Portunid Crabs

1.7 Indirect Economic Value of Portunid Crabs

1.8 Socio-Cultural Value of Portunid Crabs

1.9 Scientific Value of Portunid Crabs

1.10 Environmental Problems

1.11 Conservation of Portunid Crabs

Keywords

People living on the coast have depended on marine resources for many thousands of years. Millions earn their living in commercial fisheries, and many people still depend on seafood as their primary source of protein. The very high catch rates of modern industrialized fishing fleets have lead to widespread effects on fished species, non-target species, and marine habitats. Further, overfishing continues to be a major threat to marine ecosystems and vulnerable species throughout the world. Although dwarfed by fisheries for finfish, crab fisheries are important in many developing countries. As early as prehistoric times, blue crabs were collected for subsistence.

1.1 PORTUNID CRABS

Brachyuran true crabs (Class: Crustacea; Order: Decapoda; Infraorder: Brachyura) comprise about 6700 known species worldwide (Melo, 1996) and, due to their great abundance, they are considered as one of the most relevant groups of the marine benthos, both in terms of biomass and community structure. Man consumes many species of crabs of the families—Lithodidae, Macidae, Caneridae, Portunidae, Xanthidae, Potamidae, Geryonidae, Gecarcinidae, and Ocypodidae (Muthiga, 1986). Among these crabs, portunid crabs or swimming crabs assume greater significance in the marine industry owing to their delicate meat with nutritional qualities. These crabs, which reach their greatest species diversity in the Pacific and Indian Oceans, are distinguished from the rest of the round-fronted crabs by the adaptation of some of their legs for swimming, for which these limbs are transformed into flattened paddles. Their strong, sharp claws, allow many species to be fast and aggressive predators. They also have a power of darting at high speed through the water. Corresponding to this mobility, they have a thin flattened form of body, and a lightness gained at the expense of the protective cuticle. These crabs are benthic to semipelagic with diverse habits. Their proper haunt is a space of quiet waters, such as the lagoon of a coral atoll, and these places are generally bottomed with white or greyish coral sand. Portunid crabs have rather diversified feeding habits, including algae, vascular plants, foraminiferous species, cnidarians, molluscs, polychaetes, other crustaceans, fish and other groups. They have ecological importance in the estuarine-marine ecosystem as they serve as a food resource for other aquatic organisms, such as fish and coastal birds. True crabs make up 20% of all crustaceans caught and farmed worldwide, with about 1.4 million tonnes being consumed annually. The horse crab, Portunus trituberculatus accounts for one quarter of that total. Other portunid species of great fishery value include Scylla serrata, Portunus pelagicus, Portunus sanguinolentus, and Charybdis feriatus—each of which provides more than 20,000 tonnes annually (https://en.wikipedia.org/wiki/Crab_fisheries).

1.2 SUBFAMILIES AND GENERA OF PORTUNID CRABS

• Subfamily 1. Caphyrinae: Caphyra, Coelocarcinus, Lissocarcinus, and Mioxaiva^†.

• Subfamily 2. Carcininae: Carcinus, Cicarnus^†, Echinolatus, Portumnus, and Xaiva.

• Subfamily 3. Carupinae: Carupa, Catoptrus, Laleonectes, Libystes, Neptocarcinus^† Rakosia†, and Richerellus.

• Subfamily 4. Macropipinae: Benthochascon, Boschettia^†, Brusinia, Liocarcinus, Macropipus, Ovalipes, and Parathranites.

• Subfamily 5. Podophthalminae: Euphylax, Podophthalmus, Psygmophthalmus^†, Sandomingia^†, Saratunus^† and Viaophthalmus^†.

• Subfamily 6. Polybiinae: Bathynectes, Coenophthalmus, Falsiportunites^†, Gecchelicarcinus^†, Maeandricampus^†, Megokkos^†, Minohellenus^†, Necora, Nectocarcinus, Ophthalmoplax, Pleolobites^†, Polybius, Pororaria^†, Portufuria^†, Portunites^†, Proterocarcinus^†, Raymanninus, and Rhachiosoma^†.

• Subfamily 7. Portuninae: Acanthoportunus^†, Arenaeus, Atoportunus, Callinectes, Carupella, Colneptunus^†, Cronius, Euronectes^†, Lupella, Lupocyclus, Necronectes^†, Portunus, Pseudoachelous^†, Rathbunella^†, Sanquerus, and Scylla.

• Subfamily 8. Thalamitinae: Charybdis, Eocharybdis^†, Gonioinfradens, Thalamita, and Thalamitoides.

Note: The gene marked with bold and dagger symbol are extinct.

1.3 COMMERCIALLY IMPORTANT PORTUNID CRABS

Though majority of portunids are edible, a small number of species have been reported to be commercially important with major or minor fisheries. They are: Charybdis affinis, Charybdis anisodon, Charybdis annulatata, Charybdis bimaculata, Charybdis feriatus, Charybdis helleri, Charybdis hongkongensis, Charybdis japonica, Charybdis lucifera, Charybdis natator, Charybdis smithi, Charybdis vadorum, Charybdis variegate, Charybdis truncata, Podopthalmus vigil, Portunus gladiator, Portunus gracilimanus, Portunus haanii, Portunus hastatoides, Portunus pelagicus, Portunus sanguinolentus, Portunus trituberculatus, Scylla serrata, and Scylla olivacea.

1.4 ROLE OF PORTUNID CRABS IN AQUACULTURE

Unlike shrimp culture, portunid crab culture provides sustainable marine food supply with lesser culture duration and free from unwanted diseases. Fisheries exploitation and aquaculture production of the world’s crabs has increased sevenfold over the past thirty years. Several large of the swimming crabs are considered as candidate species for aquaculture. The most common tropical species of portunid crabs suitable for aquaculture include Scylla serrata, Scylla olivacea, Scylla tranquebarica, Scylla paramamosain, Portunus pelagicus, Portunus sanguinolentus, and Charybdis feriatus. One temperate species, Portunus trituberculatus is also considered as a suitable species for aquaculture especially in Japan. Widespread across Indo-Pacific including South-east Asia, portunid crabs are among the valuable commodities across many countries, fetching higher market price compared to other locally consumed marine fish species. Increasing capture of small-sized crabs, berried females due to high market demand and decreasing recruitment and capture fishery landing have raised concern over the sustainability of current crab exploitation practices. Thus, the development of aquaculture for portunid crabs and resources management for sustainable fisheries should be the prime focus in ensuring the continuity of availability of portunid crabs.

1.5 NUTRITIONAL VALUES OF PORTUNID CRABMEAT

Crabmeat, like fish, has been reported as a nutritious food, low in calories and fat but high in protein and omega-3 fatty acids, which help prevent heart disease. These fatty acids are especially important for women who are pregnant or breastfeeding because they are needed for their child’s developing nervous system. Omega-3s, which are higher in crabmeat than in shrimp, may also reduce inflammation, enhance immune function, and even lower the risk of certain types of cancer. Crabmeat is also rich in vitamins and minerals, with high levels of vitamin B-12, a vitamin critical for healthy nerve function.

1.6 POTENTIAL VALUE OF PORTUNID CRABS

The crabmeat is very tasty and nourishing. Crab curry is a reputed cure for asthma. Similarly, the soup made from the swimming crabs Portunus sanquinolentus and Portunus pelagicus are commonly used by the people just after recovery from malaria and typhoid. Scylla serrata serves as a cure for diarrhea and dysentery. All the edible crabmeats are rich in vitamins and are good for colds, asthma, eosinophilia, primary complex, wheezing, etc. They are also believed to stimulate brain cells. Crab shells are also used nowadays for preparing suture threads. Ointment prepared from crab shells is known to heal wounds quickly and avoids scars.

1.7 INDIRECT ECONOMIC VALUE OF PORTUNID CRABS

All the portunid crabs are indirectly important as they play a dominant role in the marine food web. The faeces of these crabs consist of carbon, nitrogen, phosphorus and trace metals which form a rich food for other consumers of the marine ecosystems. The crabs and their larvae are consumed by many predators and omnivorous fishes, and they play a vital role in the transfer of energy through the food chain. Thus they are also of immense help in recycling nutrients which enhance the richness of the soil by “ploughing”.

1.8 SOCIO-CULTURAL VALUE OF PORTUNID CRABS

Portunid crabs have been associated with religion since first century. Romans worshiped the crab as Sea God and named the crab as Neptune. The crab Charybdis feriatus was the symbol of cross by Christians from coastal areas of India. They do not normally eat this crab and let it free to swim in the sea after fishing. Portunus sanguinolentus, which has three reddish round spots each encircled by whitish ring, is considered to be the manifestation of Lord Siva who has three eyes. The abnormal growth of body cells (due to cancer/tumor) resembles the nesting ground of Cancer spp. So the generic name is used to denote this killer disease.

1.9 SCIENTIFIC VALUE OF PORTUNID CRABS

Many highly active biocompounds have recently been isolated from portunid crabs associated with antimicr...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• List of Abbreviations
• Preface
• 1. Introduction
• 2. Biology and Ecology of Portunid Crabs
• 3. Profile of Portunid Crabs (Family: Portunidae)
• 4. Aquaculture of Portunid Crabs
• 5. Nutritional Values of Portunid Crabs
• 6. Biomedical, Food, and Industrial Applications of Portunid Crab Wastes
• 7. Diseases and Parasites of Portunid Crabs
• References
• Index