| Popis: |
A pulse compression process was used to analyze echoes from individual animals of three distinct morphological groups of zooplankton. The groups studied were fluidlike animals (Euphausiids, decapod shrimp), elastic‐shelled (Gastropods), and animals containing a gas inclusion (Siphonophores). A broadband chirp signal was used to insonify freshly collected animals that were then tethered in a seawater tank either in the laboratory or on the deck of a ship. The decapod shrimp was tethered to a stepper motor and was rotated in 1‐deg increments. The other experiments had some animals fixed and others moving freely. The pulse compression processing of the echoes from the animals temporally resolved multiple returns from an individual. Using existing scattering models [Stanton et al., J. Acoust. Soc. Am. (to be published)], the temporal and amplitude differences of the returns were used to estimate size and orientation. Estimates of the size of the animal were made for the Euphausiids, Gastropods, and Siphonopho... |
