26 A BIOLOGY OF CRUSTACEA 



mandibular palps and the first maxilla, and they can move in a 

 series of rapid jerks brought about by all the limbs and the 

 abdomen with its caudal rami. The latter movement is usually used 

 as an escape mechanism, or sometimes as a means of surprising 

 prey. A few species, such as Anomalocera pater soni, can move with 

 such vigour that they can hurl themselves right out of the water, 

 and a shoal of these creatures can appear like a rain shower on 

 the surface of the sea. Another species, Pontellina mediterranea, 

 has been described as 'taking long flying leaps out of the water, 

 after the manner of a flying fish '. If this is really so it is the only 

 case of aerial locomotion among the Crustacea, apart from an 

 unconfirmed report of a large flying malacostracan sighted off the 

 Phillipine Islands. 



Some of the cyclopoid copepods are also predators. Species such 

 as Macrocyclops albidus seize their prey with the first maxillae 

 and hold it while the other mouthparts dismember it and push 

 it into the mouth. Other members of the Cyclopoida are herbivores 

 and feed on diatoms or small filamentous algae. 



The feeding habits of the harpacticid copepods are not well 

 known. Many of them appear to be detritus feeders; they creep 

 about between sand grains and undulate their bodies in a character- 

 istic manner. Others are known which feed, at least in their young 

 stages, on algae. Thalestris rhodymeniae has nauplii which live in 

 mines or galleries inside the red alga Rhodvmenia palmata, and 

 the nauplii of Dactylopusioides macrolabris live in similar mines 

 in the brown alga Dictyota dichotoma. The nauplii of both these 

 species are remarkable for the great development of the base of the 

 antenna, which bears a cutting edge and functions like a mandible, 

 while the true mandible appears to be incapable of biting. These 

 miners in the fronds of seaweeds are an interesting parallel to the 

 insect leaf miners of land plants. 



The feeding mechanism of the Cephalocarida has not yet been 

 described, but the Mystacocarida are said to be filterers, and the 

 filters are located in the maxillary region. This would agree with 

 their being placed somewhere near the copepods in the scheme of 

 classification. 



The original feeding mechanism of the Malacostraca is also 

 thought to be of the filtering tvpe. The basic mechanism consists 

 of a filter on the inner border of the second maxilla. A water 

 current is made to flow through the filter, from behind, by the 

 vibration of the maxilla itself. The base of the first thoracic limb 



