Hong Kong Polychaetes General Morphology The Importance of Polychaetes
Polychaetes (bristleworms) are marine annelids with parapodia bearing numerous setae in distinct fascicles. They are dioecious and multi-segmented. They have simple exit ducts from the gonads. Most of them live in soft or rocky environment on sea floor from intertidal to depth. They may be, but rarely, found in freshwater and terrestrial (humid), or parasitic.
The sex of most polychaetes are separate. The gametes produced in a few specialized segments are shed into the coelom and leave the body through the nephridia. After the external fertilization, a ciliated free-swimming trochophore larval is developed.
Other common features of polychaetes include: bisymmetry, metamerism, segmentation, schizocel, closed vascular system, chain nervous system, spiral and determinant cleavage.
The polychaete fauna of Hong Kong belongs to the tropical Indo-Malayan subregion of the Indo-west-Pacific province (Shin 1982). Since the 1970's, about 180 species have been reported. They belong to 146 genera and 47 families. Of these, 70 genera were not determined to species level due to the poor understanding of this fauna locally.
Polychaetes are abundant in mid and outer Tai Tam Bay and Hoi Ha Wan (Shin 1998). They can also be found in Tai Long Wan, Mirs Bay, Victoria Habour, Tolo Harbour, Tolo Channel, Cape d'Aguilar Marine Reserve, western waters and the vicinity of Waglan Island. The polychaete diversity in Victoria Habour and Tolo Harbour is low because of the pollution from sewage and development activities and the dominance of a few environmentally tolerant species such as Minuspio cirrifera (Spionidae) and Capitella capitata (Capitellidae). The diversity is also low in the western waters due to freshwater discharge from the Pearl River.
The body of polychaetes can be divided into three parts: Head, Trunk, and Tail.
| The Importance of Polychaetes
1. The dominant benthic fauna in
2. As food resource
3. As an indicator of toxic
materials and pollution
4. Production of pesticide
5. As harmful organisms
What are Sedentary Polychaetes?