CNC at MTRP
The City Nature Challenge (CNC) is a worldwide bioblitz event held on iNaturalist. This friendly global competition aims to offer scientists a yearly snapshot of all species to be found in a given area. For this, they rely on people like you and I (mere peasants) to do the grunt work and gather the data. Every year, the bioblitz starts on the last Friday of April and stretches out to the following Monday at midnight. During the four-day event, iNatters (previously mentioned mere peasants) frantically (or not) collect observations of all living things around the county. From coast to cactus, with a plethora of distinct habitats, San Diego is one of the most biodiverse counties in the US and offers a great playground for the CNC.
This year again, MTRP proved to be a treasure trove for finding many of the nearly 3,000 species reported in the county during the event. In fact the park housed nearly a quarter of all species found! Well done! Plants took the lead with 325 species, followed by arthropods (insects and arachnids) at 252 species. Birds came in first with 69 species found.
Here are some highlights of smaller critters and let’s see how much you remember about these little friends!
- @sclerobunus photographed one of the most beautiful Harvestmen species in the county: Ortholasma coronadense (https://www.inaturalist.org/observations/211056639). Its ornate exoskeleton makes it look ready for battle, in a very fashionable way. Think Game of Thrones costume! Remember Harvestmen? Are they spiders? NO! Let’s do a quick review: Both spiders and harvestman are Arachnids (remember: Arachnids, unlike insects, have eight legs and no wings), but despite appearances, they are quite different. Perhaps one of the best way to tell them apart is that a spider’s abdomen and head (or cephalothorax) are clearly two different body parts. Harvestmen have both body parts as well, but they appear as one unit, one solid block!
How many pairs of eyes does a spider have? I know you know the answer: four! Harvestmen however are just like you and I, they have one pair of eyes. Some of you are thinking, “it doesn’t matter, just like spiders they are venomous and even more dangerous!”. That is a classic urban legend. Unlike spiders, Opiliones do not have venom glands and their jaws are usually too small to cause humans much harm.
That means Harvestmen and spiders don’t have the same eating habits. Opiliones are omnivorous, consuming plant material, insects, other arachnids and even slugs or snails. Just like Grandpa Bob who is waiting for his new set of teeth, spiders are on a liquid diet. They must inject digestive enzymes to liquify their prey before eating (fortunately, Grandpa Bob just uses the blender). The harvestmen, like the rest of us, eat solid food.
- Talking about armor, and this time it’s not a costume but a genuine protection system, @fillsteak found a Diabolical Ironclad Beetle (https://www.inaturalist.org/observations/212944803) near Mission Dam.
Review: Imagine yourself laying down in the middle of the road (don’t do that) and a car comes by and rolls right over you. If you don’t die, you will at the very least sustain considerable injuries. Fast forward a few months, you are suing the driver, but the defense attorney brings in an unusual expert witness: A Diabolical Ironclad Beetle. This witness, if he could speak English, would proceed in explaining that the unfortunate accident was no fault of the driver and instead the injuries were simply a result of a faulty biological design on the part of the victim. “I can get stepped on and ran over by a car and be just fine” he would boast. This expert witness, a 2-centimeter long beetle in the Zopheridae family, looks like he is sporting a medieval-like exoskeleton with a slitted walnut-shell-looking surface.
In recent years, experts have “cracked” open the mystery of the beetle’s secret armor and it’s all in the design. After many analysis, 3-D printed models and computer simulations, they found that the exoskeleton’s incredible resistance to impact is a direct result of an interlocking puzzle-like structure paired with impact-absorbing proteins. Considering the amount of pressure the beetle can withstand (about 39,000 times its own body weight), it is no wonder that engineers are looking to imitate and recreate the Diabolical Ironclad Beetle’s blueprint. Read more in this article (https://engineering.uci.edu/news/2020/10/uci-materials-scientists-discover-design-secrets-nearly-indestructible-insect).
- I was very surprised to see that the Phoenix Jumping Spider (Phidippus phoenix) was the 9th most observed arthropod in the park during the bioblitz, with 40 observations! Upon further inspection, it turns out that @ptwnhustle made 35 of these observations along a single stretch of trail. That is not something many users take the time to do very often, but it really give us a lot of information about the abundance of this particular species on that trail. Here is one of the observations they made of this super cute “jumper”: (https://www.inaturalist.org/observations/216388460). How much do you remember about the Jumping Spiders?
Review: Jumping spiders are fascinating creatures and are pretty darn cute! Maybe it is easier to relate to them because two of their eight eyes are considerably bigger and located on the front of the face. This gives them a more ‘human’ look. They are also small in size and come in a variety of colors and patterns. Jumping spiders are amazing athletes able to propel themselves up to 50 times their own length. To achieve this without many muscles at all, the jumpers use controlled blood flow. A sudden rush of blood to the legs will cause them to extend in a burst. The ability to jump is what helps them be proficient hunters. Jumping spiders do not build webs to catch their prey, they actively stalk them and ambush them using a variety of intricate tactics. Even though jumpers don’t build webs, they can and do produce silk. In fact, before they jump, they usually anchor a string at the original spot and if they miss their target, they can simply use the lifeline to come back to safety. They also build silk shelters for themselves where they can hide away from predators and rest. Want to see a jumping spider in action? I highly recommend this BBC Earth video (https://www.youtube.com/watch?v=UDtlvZGmHYk) which follows an incredible hunter named Portia in her quest to her next meal. To see the fun mating dance some males perform to woo the ladies, check out this video (https://www.youtube.com/watch?v=uGZwZlcCnDE) filmed in a lab at the University of Pittsburg.
And if you are brave enough, next time you encounter a jumping spider in your house or yard, try holding a small mirror in front of them. They will often interact with the reflection (true and tried by yours truly :).
- @jilllingnell caught a glimpse of a California Bee Assassin (https://www.inaturalist.org/observations/210529893) on the North Fortuna Mountain Summit Trail. It’s all in the name! If you ever thought of bugs as cute creatures that sip flower nectar and fly carelessly in the wind, the Assassin Bug will change that perception. Bugs in the family Reduviidae (Assassin Bugs) are ambush predators. While often found on beautiful blooms, they are not there to enjoy the colorful scenery and sweet fragrance.
The assassin bug is waiting for other insects to visit and when the opportunity presents itself, it will pounce on an innocent bystander: a bee, a fly, a caterpillar, etc… The assassin holds onto its victim tightly and stabs it with its long straw-like beak (the rostrum). Just a few seconds after receiving an injection of toxic saliva, the target is paralyzed. The venom will soon start to liquify the prey’s insides and the bug “milkshake” is ready to be enjoyed. Bon appétit!
Like all true bugs, reduviidae have incomplete metamorphosis. It means that after the eggs hatch, the ‘kids’ will go through several nymphal stages (often 5) called instars. Between each instar, the bug will shed its exoskeleton to make room for a larger one, allowing for growth. At each instar, the bug may look slightly different and will finally molt one last time to reveal the adult form. Our observation from the City Nature Challenge is a beautiful adult.
Assassin bugs are incredible allies in the garden and can help control many pests. They are not aggressive toward people, but can bite if threatened or handled carelessly. Their venom is no threat to humans, however certain species (Kissing Bugs, subfamily Triatominae) can carry diseases so if bitten it is best to seek proper medical advice.
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