Some mechanical and morphological properties of the chorions of marine teleost eggs

Abstract

The eggs of plaice, Pleuronectes platessa, lumpsucker, Cyclopterus lumpus, and capelin, Mallotus villuses, were investigated. Chorion strength was measured in three ways: by tearing isolated chorions, by bursting eggs, and by penetrating eggs with a fine needle. The results obtained showed that tearing resistance and bursting pressure (which both rise after activation of eggs in sea water) are closely related to one another, both reflecting resistance to circumferential tension. Penetration pressure (corresponding to resistance to radial penetration, i.e., hardness in the materials sense) also rises, but the time‐scale of the rise differs from that of bursting resistance, particularly in the case of capelin eggs which become ‘hard’ in the sense that they resist high bursting loads, but have a ‘soft’ chorion which does not resist penetration. Differences in chorion strength between species, and alterations in chorion strength during egg development within species, are related to morphological features and changes.