The arthropods are the only phylum covered in my course that is split over multiple sessions, and with good reason. Arthropods are a majority of the species known to science. Parse that carefully: not a majority of invertebrate species. Not a majority of animal species. A majority of species, period.
That massive diversity means that arthropods are also impressively different from one another across their various groups, and covering that diversity requires an extended fraction of the lecture course’s time and two entire lab sessions. Which groups are covered in which sessions changes from year to year, so for this series I’m doing the three “classical” arthropod subphyla–crustaceans, chelicerates, and “atelocerates”–each as their own post. Today’s topic is crustaceans.