Aspects of the Biology of the Squat Lobster, Munida rugosa (Fabricius, 1775)

Zainal, Khadija Abdulla Yousuf (1990) Aspects of the Biology of the Squat Lobster, Munida rugosa (Fabricius, 1775). PhD thesis, University of Glasgow.

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The thesis presents a comparative study of respiratory physiology of the galatheids Munida rugosa (Fabricius, 1775) and M. sarsi Huus, 1935. Both species were obtained from the Firth of Clyde, M. rugosa from a depth range of 8-115m and M. sarsi from 95-115m depth. To provide background information for this study, some aspects of the general biology of both species were studied, with greatest emphasis given to M. rugosa. Both species were collected mainly from sandy muds using creels and trawls. Studies of relative growth were carried out and indicated that sexual differences were particularly apparent in cheliped lengths (positive allometry in males) and abdomen widths (positive allometry in females). Heterochely was observed in both species and, although there was much variation, it was more commonly seen in large males. Extrapolation of relative growth regression relationships for males and females suggested that, in M. rugosa, sexual maturity occurs at approximately 17mm carapace length and at approximately 10mm carapace length in M. sarsi. Preliminary studies on the reproductive cycle of M. rugosa indicated that ovary development occurred between spring and autumn. Ovigerous females were observed between November and May, and egg hatching occurred from March. There was a significant trend for larger females to carry a larger number of eggs than smaller females. Mean egg diameter was 0.89+/-0.08mm. Dietary analysis and observations of feeding behaviour indicated that M. rugosa is an omnivore with a preference for animal material. As well as feeding on macroscopic material, this species was also observed to deposit feed. The feeding behaviour of M. sarsi was similar. The morphology of the mouthparts and stomach of M. rugosa are described and related to feeding. Some comparative information on M. sarsi is also provided. A comparative study was made of the respiratory physiology of M. rugosa and M. sarsi. The gill formulae for the two species are presented. Gill areas were very similar and both species were characterized by having very low gill area values compared with other decapod crustaceans. This has been interpreted as reflecting their relatively inactive lifestyle. Studies of cardiac and ventilatory activity were made for both species. It was observed that there was usually a high degree of bilateral coordination of scaphognathite activity with periods of reversed beating and cessation of scaphognathite activity occurring synchronously between both scaphognathites. In general, cardiac and scaphognathite activity were closely correlated. This was particularly evident in quiescent animals when periods of cardiac arrest were accompanied by cessation of scaphognathite activity. The effects of temperature and oxygen availability on rates of oxygen consumption and on heart and scaphognathite rates were studied. The rates of oxygen consumption of both species were low compared with those of most other decapod crustaceans. Both M. rugosa and M. sarsi were found to be quite tolerant of hypoxia (Pc range 39-56 Torr). Survival under complete anoxia, however, was limited to 8 hours in M. rugosa and to 4 hours in M. sarsi. The oxygen and carbon dioxide transporting properties of the blood of both species were also studied. No significant differences were found between the concentrations of the major ions in the blood of M. rugosa and M. sarsi. It was noted that the concentration of Mg2+ ions in the blood of both species was higher than in many other decapods. Values for the oxygen carrying capacity of the blood of M. rugosa and M. sarsi were similar (1.7-1.9 ml. 100 ml and were within the range of values previously recorded for other decapod crustaceans. Oxygen dissociation curves were constructed spectrophotometrically using a diffusion chamber. The haemocyanin of both Munida species was found to have a low oxygen affinity (P50 = 20-39 Torr and 49 Torr in M. rugosa and in M. sarsi respectively at 10

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Zoology
Date of Award: 1990
Depositing User: Enlighten Team
Unique ID: glathesis:1990-78167
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 28 Feb 2020 12:09
Last Modified: 28 Feb 2020 12:09

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