In the deep, no one can hear you scream
The vast expanse of the seas is our destination, and uncontrollable terror is our goal. Join us as we descend into the madness that only total darkness can bring. The deep holds many secrets, and we shall share them with you...including inspirations for sea serpents (Oarfishes - including the photo here taken by our own Leo Smith), fierce predators that hide behind shimmering lights (Anglerfishes), and even the secrets to zombification (Pufferfishes). Caution, don't try zombification at home. Seriously, we don't recommend it. We hope you enjoy our special Halloween and spooky season podcast!
Have you ever swam at your favorite local spot and encountered a piranha? Believe it or not, this happens across North America all the time - not just in late night B-movies! So how does a fish that is native to South American freshwater rivers find itself living in a Missouri pond? Often these invasive species (a term that describes biodiversity that is introduced into a non-native environment and locale) are simply dropped off by pet-owners that are releasing them into the wild. In some cases invasive species take hold in a non-native environment purely through accidental circumstances. Occasionally, invasive species are purposefully placed in a locality because someone thought they would serve a specific positive purpose. For example, mosquitofishes (Gambusia affinis) have been frequently introduced in non-native habitats because people wanted them to control mosquito populations. Join us and our special guest, Caleb McMahan, as we discuss this environmentally important topic.
Introducing non-native species frequently has negative effects for the local environment and biodiversity. Invasive species can dramatically alter the fragile ecosystems they are introduced into and severely threaten native wildlife. One example of an introduced fish that has reeked havoc on the native fishes of Illinois is the Round Goby (Neogobius melanostomus). The Round Goby was introduced into the Great Lakes (including Michigan) through freighter vessels traveling from the Black Sea. Once the Round Goby was accidentally brought to the lakes they began spreading at a rapid pace.
Unfortunately, the increase in these invasive gobies has harmed many native fish populations, such as the Mottled Sculpin (Cottus bairdi). Round Gobies are voracious predators on the eggs and fry of other fishes and they are fiercely territorial with their spawning sites. This creates competition with native fishes for reproductive space. Another invasive species in Illinois is the Grass Carp from Asia (Ctenopharyngodon idella), which was purposefully introduced in the United States in an effort to control aquatic weeds. The introduction of the grass carps into non-native habitats was carefully controlled, and many of the introduced populations were gentically modified to be sterile in an effort to curb unwanted population growth in the wild. Despite these precautions, populations of Grass Carp have spread across the United States since their intial introduction in the 1960's.
2.5 million specimens don't collect themselves!
The Field Museum's Division of Fishes houses approximately 2.5 million specimens of fish, including whole specimens in alcohol, skeletal specimens, tissue samples, and cleared and stained material. That is a lot of fishes! But the fishes did not just arrive overnight; scientists and researchers have been adding to the collection at The Field Museum since 1894.
Museum collections serve as records of the natural world, as well as critical resources for scientists wanting to study the biodiversity of the planet. The fishes collection has grown through continued fieldwork by ichthyologists that use a vast array of tools and strategies for sampling living and extinct fishes from around the world. Tune into our podcast this week with a special paleoichthyological guest, Sarah Gibson of the University of Kansas. Listen to us as we discuss the many different ways we collect fishes in the field.
The allure of sharks
Sharks, and cartilaginous fishes in general, have long mesmerized scientists and the public alike. They are fascinating creatures! Fossil remains indicate that sharks have been evolving on this planet for well over 400 million years. They have been described in popular culture as "perfect killing machines," and it is hard to argue with their abilities to hunt and secure prey of all shapes and sizes. Be it the incredible filter-feeding of the immense Whale and Basking sharks or the pure power and incredible bite of the Great White Shark, few organisms in nature portray an aura of such efficiency. Sharks are among the earliest known jawed-vertebrate lineages, and since their initial evolution, they have wasted no time in putting those jaws to work. After 400 million years they still remain some of the oceans most incredible predators with no signs of slowing down.
Sharks are venomous and bioluminescent?
However, there are more to sharks then just teeth! A number of lineages have independently evolved venom, including the horn sharks and angel sharks. The horn sharks release venom out of spines that stick out from each of their dorsal fins, making them an unattractive meal for even larger predatory fishes. The spines of the dorsal fins in some squaliform (or dogfish sharks) are also known to be venomous, including species within the lanternsharks. Sharks have also independently evolved bioluminescence, the ability to generate and emit light, as they have invaded the deep sea. These include predominantly deep-sea taxa, such as the lanternsharks and the bizarre Cookie Cutter Shark that sucks on to prey and rips off hunks of flesh before speeding away. These deep-sea sharks all use bioluminescence to hide from potential prey items, to avoid being eaten themselves, and for communication.