Section 2 â¢ Invertebrate Chordates 803 Chordates are animal s belonging to the phylum Chordata (kor DAH tuh) that have four distinctive featuresâa dorsal tubular nerve cord, a notochord, pharyngeal pouches, and a postanal tailâat some point during their development.ost chordates are vertebrates. Invertebrate chordates, which belong to two of the subphyla of chordatesâCephalochordata and Urochordata, also have a dorsal tubular nerve cord, a notochord, pharyngeal pouches, a postanal tail, and, possibly, an ancestral thyroid gland. They ha ve no backbone, however.
quack 1. (kwÄk) n. The characteristic sound uttered by a duck. intr.v. quacked, quackÂ·ing, quacks. To utter the characteristic sound of a duck.
1. rucksack-a bag carried by a strap on your back or shoulder. back pack, backpack, haversack, knapsack, packsack. bag-a flexible container with a single opening; he stuffed his laundry into a large bag. kit bag, kitbag-a knapsack (usually for a soldier).ucksack. n. 1. a large bag, usually having two straps and a supporting frame, carried on the back and often used by climbers, campers, etc. US and Canadian name: backpack. [C19: from German, literally: back sack].