It has been suggested that the decline in sandbar sharks that occurred along the mid-Atlantic states in the last 1980s to early 1990s resulted in a significant increase in populations of the chain catshark.   As you may remember from class, Grubbs proposed that there are several criteria or diagnostics that must be considered when evaluating whether a hypothesized trophic cascade has truly occurred.  They are shown in the picture below, along with temperature preference data for these two species and other elasmobranchs. Based on these data, which of the listed criteria do NOT support this hypothesized trophic cascade?     

The picture below shows a typical chondrichthyan heart, in which the 4 subcomponents have been labeled using letters (a – d).  The arrows in the picture refer to the direction of blood flow. Match the letters below with the appropriate subcomponents of the chondrichthyan heart.  

Which of the following species is known to gulp air to aid in maintaining neutral buoyancy?

In early work on shark behavior, the “Shark Lady” Dr. Eugenie Clark demonstrated that she could train subadult and adult nurse sharks to press targets to receive food rewards. What type of behavior is this?

Which of the following structures is used to maintain neutral buoyancy in the Chondrichthyans?

What is the nature of the relationship between temperature and metabolic rate in the chondrichthyans?

Let’s say that we grouped all fishes (the jawless fish, cartilaginous fish, and bony fish) into one taxonomic group known as “the fishes” because of their similarities, excluding all other animals. What type of grouping would this group be?

What is the name of the fin that is labeled with the black arrow in the picture below?   

I recently was part of a team charged with assessing the status of the smooth dogfish (Mustelus canis) population on the U.S. Atlantic coast.   The graph below shows the size (in fork length, which is from the tip of of the rostrum to the “fork” in the caudal fin) of smooth dogfish caught in a fishery-independent survey conducted off of Virginia from 1994-2012.  The diamonds represent individuals animals and the line represents a trendline. Based on these data, is the phenomenon known as juvenescence occurring in this population?   

In which of the following structures would you expect to observe rugae in?