Invertebrates

(1) Invertebrate diversity in China

The number of groups and species of invertebrates hold a dominant position not only in the kingdom Animalia but also among all life-forms on earth. According to Groombridge (1992), the described species of invertebrates (1.325 million) accounts for 96.71% of the total species of animals (1.37 million), and 76.19% of all life-forms (1.739 million).

The total diversity of the invertebrates is still unknown. At present, some 15,000 new species are described each year. At this rate of progress it will take 100 years at least to record all the species that possibly exist. China has a large territory and a rich species diversity, but knowledge about the country's resources is still insufficient. In general, Chinese species of animals possibly account for one tenth of the total number on earth. The numbers of some groups, such as the Porifera, are relatively small because of insufficient study. Conversely, some groups have a higher percentage than one tenth. These are groups containing most of cosmopolitan species, such as the Rotifera and Cladocera, some marine groups with few geographical barriers, such as the Chaetognatha, Phoronida and Antipatharia (Cnidair), and groups well surveyed. Such groups can be listed as follows: Antipatharia making up 87.5% (a total of 80 species, some 70 species in China), Leptomedusae 84.7% (210 species in total, 178 in China), Chaetognatha 52.4%, Anthomedusae 44% (239 species in total, 129 in China), Phoronida 40%, Rotifera 40%, Cladocera 35.7% (450 species in total, 161 in China). The Protozoa cannot be put into the appendix because of controversial views with regard to the classification of the Kingdom Protista and a lack of data. It is reported that the protozoans (excluding the composite forms with algae or with fungi) comprise 31, 250 extant species or 63, 616 species, if the fossil forms are included. Among these, 21,100 species are free-living and 10,150 species are parasitic. Of the free-living protozoans, between 5,000～6,000 are freshwater species. China has 2,000 known species, accounting for between 33%～40% of the total. There are 300 soil species and 159 of these occur in China, accounting for 53% of the total. There are 3,600 marine protozoans in China, accounting for 23% of the total number of 15,100 species.

Being in a special position in the process of evolution, China is rich in species, especially endemics, including many “living fossils”. Species diversity in China, therefore, constitutes an important part of that of the world. There are numerous endemic genera and species in China. For example, the hydrozoan Craspedacusta (Hydrozoa), has a total of five species and four subspecles. China has four species including three endemic species and four endemic subspecies. In the Turbellaria (Platyhelminthes), the endemic species occurring in China are: Phagocata, two of the total of three species; Polycelis, all nine species; Dendrocoelopsis, all two species. The 43 known sipunculans in China contain eight endemic species. Of the eleven species of Echiura, four are endemic, including the endemic genus Para-arhynchite. This is fairly typical of marine animals. It seems, however, that the most notable examples are found in the animal groups living in freshwater or on islands. For example, there are five endemic genera and 132 endemic species of land snails in China. The freshwater Bivalvia contains six genera and 26 species endemic to China. Of the known 206 species and subspecies of Copepoda (Crustacea) in China, 96 are endemic, accounting for 46.6%. The freshwater crabs can be regarded as a typical case. Different genera and species have evolved because they live under stones in streams isolated from each other in mountainous areas. Of the 35 known Benera, there are 32 endemic genera accounting for 91.4% of the total and 250 endemic species. The Myriapoda (Unirama) is another example. The Sinollipodidae is a family endemic to China. Two other families have 3 endemic genera and 9 endemic species. The examples above show clearly that it is an urgent task to study China’s biodiversity in order to globally identity all invertebrate species.

Invertebrates are of importance for scientific research. For example, only after a detailed study of invertebrates can yon obtain correct answers to the following questions: the evolntionary process from unicellular to multicellular, from radial to bilateral symmetry, from diploblastic to triploblastic, the phylogeny of different animal groups, and some great events sach as the origin of life and the origin of metazoans. Animals with quite different structures face the same problems: feeding, defense, movement, respiration, excretion, ionic and osmotic regulation, controling systems, reproduction, life cycle and development. They solve these problems using different structures and ways to adapt themselves to different environmental circumstances. Invertebrates hold a dominant position not only in terms of species divetsity but also in their diversities of structure and behaviour. For example, the protozoans are important for studying the origins of life and the cell, The relationships between lower plants and animals, and how the protozoans evolved into metazoans. The Acoela, a primitive group of turbellarians of flatworms, have a key position in the evolutionary process from a diploblastic form with radial symmetry to a triploblastic one with bilateral symmetry. To study the origin of vertebrates one should first study their invertebrate kin as well.

Living invertebrate fossils are of special scientific significance. For example, Heptathela, with segmented tergites on the abdomen, is the most primitive group in the present 105 families of spiders. Most species of the genus are distributed in China. Another living marine fossil is Nautilus (Cephalopoda) which is important in the evolution of the Mollusca as well as in palaeoecology and palaeoclimatology.

Invertebrates are related directly to the quality of our life because they comprise most species of animals and can be found in every habitat that animals can live in. Many invertebrates are beneficial. First, many are used as food. The annual output of marine cuttlefishes, shells, shrimps and crabs is enormous. Invertebrate cultivation makes up a large portion of seawater aquaculture. The output of fishes is far inferior to that of invertebrates. Though the freshwater aquaculture of prawns and crabs yields less than seawater, the capture of these crustaceans in the wild is significant, for example, the shrimp Macrobrachium nipponense and the crab Eriocheir sinensis and the molluscan genera Cipangopaludina, Bellamya, Margarya, Anodonta and Corbicula. Most mollusks and crustaceans introduced from abroad during the past years are economically significant.

Second, many invertebrates, such as protozoans, rotifers, the brine shrimp (Artemia salina), water-fleas and copepods are the food of economic fishes. Many terrestrial invertebrates are also prey organisms of vertebrates. Many can be utilized as materials in industry, processed into handicraft articles, or articles in everyday use, and for medicine. Invertebrates can improve the soil, be environmental monitors, display animals, and the natural enemies of insect pests. Some groups of marine protozoans can be used as indicators for identitying strata in the earth, e. g., the appearance of Hyalina balthica and Globorotalia truncatulinoides (Foraminiferida) marks the beginning of the Quaternary. Of course, many are harmful. Some are parasites of Man and domestic animals, the intermediate hosts of parasites, or species infesting crops and damaging buildings and ships. Invertebrates have a great impact on human life, both advantageously and disadvantageously

because of their ubiquity and their importance in every ecosystem.

(2) Threatened invertebrates in China

Usually no attention is paid to the threatened status and extinction of invertebrates because of their smallness. Many rare and endangered species have, therefore, become extinct, even before being described or listed in the Red Book. For example, a big bird spider (Theraphosidae) in Mount Jianfenling, Hainan, is probably extinct.

The main threats to invertebrates are the destruction, or loss, of their habitats as well as environmental pollution. Animal resources have declined rapidly because of over-exploitation. These two factors have bought many animals to the verge of extinction.

Among the freshwater invertebrates, many species need a low temperature and pure, flowing water. Diverting water from streams or springs, pollution, or the eutrophication of water results in their endangerment. Protozoans, e. g., Amoeba, Porifera (freshwater sponges), cnidarians (Hydra, Craspedacusta), Platyhelminthes (Turbellaria), Rotifera, Nematoda, Annelida, Crustacea (Cladocera, Copepoda, Amphipoda) and aquatic insect larvae are not able to survive under such circumstances. For example, the increasing consumption of water for domestic and industrial purposes has led to a lowering in the underground water table. The water resources of springs have been destroyed resulting in the extinction of many animals, such as turbellarians. Springs located in the following places are badly in need of protection, Yuquanshan (Lanzhou). Yingtaogou (Beijing), Qianshan. (Anshan), Lingyin and Longjing (Hangzhou) and others. The long-term monitoring of East Lake in Wuhan, Hubei Province, has indicated that the community of emergent water plants has withered, even disappeared, because of eutrophication and fish culture. Many animals depending on such aquatic plants have lost their preferred habitat. Studies have shown that more than 80 species of rotifers present in East Lake in the 1960's have declined to only 50 in the 1990's. Many species of the genus Lecane and Lepadella patella and Wolga spinifera cannot now be found in the lake.

Large numbers of invertebrates with notable scientific significance have become either endangered or extinct due to deforestation, especially because of the rapid cutting of tropical rain forests. The remarkable cases are the theraphosids in Hainan and the whipscorpions Typopeltis (Uropygi, Arachnida) in Yunnan mentioned above.

Some old species, such as the scorpion Buthus martensi is very sensitive to noise and pesticides. As a resource of Chinese traditional medcine, populations of the scorpion are rapidly declining along with the development of modern agriculture and transportation.

Cave animals have become endangered because of exploitation for tourism and include many endemic species, such as the spider Telema wunderlichi, the millipede’s Sinocallipus simplipodious and Scleroprotopus membranipedalis, and cave crustaceans.

There are many examples of endangered species due to over capture for handicrafts or tourism. Vast amounts of coral have been collected. Antipatharian corals grow slowly and it is difficult for coral reefs to recover after damage. Recently, large quantities of corals have been excavated for construction and making lime, resulting in a great damage to the ecological balance of the reef. In the past ten years, the coastline at Baitang Village, Wenchang County, Hainan, has retreated some 200 meters due to the destruction of the offshore coral reef. Coconut trees fell and the village was inundated by seawater. The destruction of the coral reef also broke the highway along the seashore at Sanya, Hainan Province. Porites lutea is a key species during the initial stage of recovery and succession in a coral reef. It is estimated, however, that it will take between 50～100 years for the species to resume its flourishing growth stage. A proposal to transplant hermatypic corals to damaged areas has been put forward with the aim of shortening the recovery period of the coral reef ecosystem in Hainan. Artemia salina is an example of an organism suitable for feeding to cultured fish. This resource was once rich in China, but it has now become an imported commodity. The resources of the crab Eriocheir sinensis have decreased sharply due to overfishing of their megalopae. Two species of the genus Margarya, M. melaniodes and M. mansuyi, can be identified as another such case. These two endemic snails living on the Yunnan Plateau are of high food value. Recently, they have become endangered by heavy pollution of lakes and overfishing. Three species of prawns belonging to the genus Caridina, namely C. gregoriana, C. yui and C. dianchiensis, were collected for consumption, but now they too have disappeared. For example, Dali Lake (Er Hai), in Yunnan, had a high production of C. gregoriana, but no specimen has been found since the 1980's. Besides overfishing and pollution, the irrational introduction of exotic species is an important factor endangering native and endemic ones.

(3) The conservation and sustainable use of invertebrates

The following invertebrate taxa (excluding insects) are listed in the National Catalogue of Protected Wild Animals. First class status: Corallium (Anthozoa, Cnidaria) and four other species, i. e., Tridacna cookiana (Bivalvia) and Nautilus pompilius (Cephalopoda), Glossobalanus polybranchiporus and Saccoglossus huangtauensis (Enteropneusta); Second class: Cypraea tigris and Cassis cornuta (Gastropoda), Pinctada maxima and Lamprotula mansuyi (Bivalvia). Based on our estimation, the list (including insects) should contain about 10,000 species. According to the list in the "Convention on International Trade in Endangered Species of Wild Fauna and Flora", all species of the Liphistiidae and Theraphosiidae (Araneae), Tridacnidae and Lamprotula spp. (Mollusca), and all species belonging to the Scleractinia and Antipatharia (Anthozoa) should be listed in the Chinese catalogue mentioned above. Many regions in China, however, remain to be surveyed, for example, the tropical rain forests of Hainan and Yunnan Provinces and Mount Shiwandashan (Guangxi Province). Many rare Chinese species need to be described as soon as possible. Much work on invertebrates is still ahead for Chinese taxonomists. Today, however, no work can be done because of the shortage of research funds for field expeditions. Compared with the studies of vertebrates, knowledge of the species and the distribution of invertebrates is still very insufficient. The investigation and description of these animals must be regarded as the first step in the study of invertebrate diversity. We must make up deficiencies in as short a period of time as possible. Otherwise we can say nothing more about the problems of invertebrate biodiversity protection.

Regarding those edible invertebrates, especially the marine cuttlefishes, shrimps, crabs and shells, the prevention of overfishing is the most urgent task from the view of sustainable utilization of their resources.