Species of the Month

Halloween is just around the corner. Traditionally, we examine a spooky critter with a connection to Halloween for the Species of the Month. This year let’s try something different. There’s nothing scary about a ghost crab, but its name fits the season. 

Ghost crab (Science Magazine)

Scientific name: Ocypode quadrata 

Kingdom: Animalia (animals)

Class: Malacostraca (soft-shelled crustaceans)

Order: Decapoda (ten-footed crustaceans)

Range: Rhode Island to Brazil 

Habitat: Ocean or estuary beaches, from the tide line to the dunes 

Lifespan: 3 years 

Diet: Bean clams, mole crabs, sea turtle eggs and hatchlings, organic detritus 

Predators: Shore birds, gulls, raccoons 

Conservation status: No special protection

Other info: Ghost crabs are small, nocturnal crustaceans. They grow to about a two inch carapace (back shell) with long legs and eye stalks, and their claws are uneven sizes. Ghost crabs hatch from an egg in the ocean and go through six larval stages before developing into adult crabs. Unlike other crabs that can only mate when the female is molting, ghost crabs can and do mate at anytime after reaching maturity which is usually after a year old.  

Juvenile ghost crab (NPS)

Ghost crabs live in burrows in the sand. They plug the holes during the day and emerge at night for feeding and mating. Mating occurs near the male’s burrow. They travel several feet per night and may not return to the same burrow. Occasionally they will go into the water to wet their gills; they are also capable of absorbing water from the sand into their gills. 

Ghost crabs can be used as an indicator species to monitor the health of their habitat. Populations can be easily estimated by counting burrows. Knowing the status of the crab population can tell what kind of impact human activities are having on the ecosystem overall. Off road vehicles and coastal development are the biggest challenges we give them. 

A pair of ghost crabs (NPS)

Once again this week's information comes from the Animal Diversity Web at University of Michigan. Next week is a rerun. We'll have fresh content after Halloween. Stay tuned!

The Ozarks

 Last month I visited family in Missouri. I'd been through Missouri many years before, and remember it being mostly flat. I was travelling out of St. Louis towards Kansas City then. This time, I went southwest out of St. Louis. The road was like sailing the ocean over the waves. Up down one hill then up the next. I always thought the Ozarks were in the southwest corner of the state. It turns out pretty much the whole southern half of Missouri is Ozarks. The undulation leveled out a bit once I reached the Springfield Plateau in the southwest. But it was nowhere near as flat as Illinois.

The wildlife in the Ozarks is different from what I'm used to in Pennsylvania. However, I didn't get to see very many new critters. There are freshwater clams in Stockton Lake. I saw plenty of armadillos, but they were all dead. No roadrunners, no rattlesnakes, no scorpions, and no tarantulas. I saw some insects that I have at home, like a wheel bug, a milkweed bug, and the ubiquitous deer. Southern leopard frogs in a spring house at a Civil War battlefield was a nice surprise.

Wheel bug

Bird poop moth

Milkweed beetle

Black swallowtail

Freshwater clam

There was more forest than I expected to see. I got to check out some oak savanna. Most of the land in the Springfield Plateau that I saw was farmland. There were some crops, mostly corn, but the majority was cattle pasture.

It was nice to see some butterflies finally. Compared to last summer, I haven't seen very many this year. Apparently once you leave Bucks County they are everywhere. The Flight 93 memorial in western Pennsylvania has quite a few grasshoppers too. Turkeys flew across the road ahead of me somewhere in that area. Elsewhere, the sky was full of turkey vultures and hawks that I couldn't identify. A fox ran across the road ahead of me in Indiana.

Dead luna moth

Fence lizard

Fritillary (left) and buckeye (right) butterflies

Southern leopard frogs

Dead armadillo

Even though I didn't set out to explore nature on this trip, it still happened. It happens everywhere I go now that I've been trained to see things everywhere. Next time you are out and about, take a look around and notice what you see.

Tiger swallowtail

Oak savanna

Species of the Month

With Thanksgiving just a week away, once again we turn our attention to the dinner plate. In years past, November's Species of the Month has featured the wild turkey, venison, and clams that were likely present at the first Thanksgiving. This year, we look at a staple of the modern celebration, the North American cranberry.

Whole berry cranberries (UWLC)

Scientific name: Vaccinium macrocarpon

Kingdom: Plantae (plants)

Class: Magnoliopsida (dicots)
Order: Ericales (heath)

Cranberries on the shrub (UWLC)

Range: US west coast, northeast US and Great Lakes areas
Habitat: Bogs with acidic soil
Diet: Water and sunlight
Predators: Bears, rodents, birds, deer, humans
Conservation Status: Listed as endangered in Illinois and threatened in Tennessee

Cranberry bog

Other facts: Cranberries grow in freshwater peat bogs. They are grown commercially for use in food products. The best use is the canned jellied cranberry. Cranberry plants are useful as a food source for animals. Birds, bear, and rodents eat the berry, while deer browse the shrub. Birds and rodents also use the stems for nesting material. Birds may also build a nest in the shrub. Cranberries also form a symbiotic relationship with fungi, giving up sugar in exchange for access to soil nutrients. Cranberries can survive being submerged for long periods, and even being kept on ice over the winter.

Cranberry flower (Cape Cod Cranberry Growers)

This week's information comes from Cape Cod Cranberry Growers Association, USDA PLANTS, and University of Wisconsin- La Crosse. Pictures, except the flower, are also from University of Wisconsin- La Crosse.

Getaway Islands

Summer is here and for many people it's the perfect time to relax at the beach. If you're at an East Coast beach, odds are you're on a barrier island. The Atlantic barrier islands extend from Canada to Florida, then up Florida's Gulf Coast and all the way around to Mexico. Prior to development, many of these islands came and went at the whims of the tides and storms. Now that we've built homes and resorts on them, there is a vested interest to make them more permanent by using jetties to block the outflow of sand and beach replenishment to restore what's been lost. Let's take a look at the natural history of where you built that sand castle.

Grassy dune in New Jersey

Barrier islands, if left to nature, live and die by the tides. Ocean currents carry sand away from the islands. The sand either moves out to the sea floor, where it can be brought back to the island by currents, or it is carried to another part of the island or to a different island. Strong storms can accelerate the process, wiping islands off the map or opening up a new inlet to the back bay.

Hurricane Irene cut these inlets across Hatteras Island (NOAA) 

Barrier islands can move toward the mainland as wind blows sand over the dunes to the bay side. The marshes fill in with sand and build up new dunes, while ocean moves to where the dunes originally were and new marshes form in the bay on the edge of the old marshes.

Salt marsh at Assateague Island (NPS)

The islands are important because they are barriers protecting the mainland from such storms. A few weeks ago we looked at hurricanes on this blog. Barrier islands absorb the brunt of the storm surge that comes in ahead of the hurricane. Developed barrier islands still absorb the storm surge, but not as well as undeveloped islands from times past. Impermeable surfaces like roads and parking are terrible at absorbing water, while sand drains quickly. If the dunes have been removed from an island, the storm surge rushes right over top with nothing but buildings to slow it down.
Barrier islands are also important as habitat for critters other than summer vacationers. On an undeveloped island, different plants and animals that can tolerate different amounts of salt water and exposure to the air make their homes in different zones. Clams live beneath the sandy shore, while birds that prey on them scurry above. Grasses hold the dunes in place, and at the highest points of the island you can find trees and shrubs where songbirds and mammals live. Brackish marshes on the other side of the dunes host crabs and serve as a nursery where fish can eat and grow before venturing into the open sea. Wading shorebirds take advantage of this bounty. Beyond the marsh is the back bay and the mainland.

Ghost crab (NPS)

Sandpiper feeding frenzy

The US has more barrier islands than any other country in the world. Best known are New York's Fire Island, Texas's South Padre Island, the Outer Banks of North Carolina, and the Jersey Shore. If you spend a summer weekend at the beach, be sure to check out the wild side of things.
This week's information comes from Science News for Students.

Animal Attraction

People are more like animals than we like to admit sometimes. Rather, we tend to believe that animals can be so human sometimes. One area where the lines between humans and animals can become blurred is that of courtship rituals and relationships. This Valentine’s Day let’s look at “love” in the animal world. Hopefully our finned, feathered, and furred friends don’t feel as awkward as we do.

Many times, in the animal world it is the female who chooses a mate. Males might compete with each other not by fighting, but other means. Bowerbirds build little houses with decorated yards to impress females. Prairie chickens and sage grouse gather in a lek, where the males display for the females. South American birds called manakins show like an 80s break dance fight from a movie. It reminds me of teenage boys trying to upstage each other to get a girl’s attention.

In other species, brute strength carries the day for males eager to win mating rights. Large mammals like elk and bison have a dominant male who controls a harem of females, unless a younger and stronger challenger is able to put him out to pasture. This behavior reminds me of countless schoolyard and lunchroom fights over a girl.

Once these critters become an item, how long does their relationship last? It depends on the critter, just like with us. Some species are monogamous pairs, some are promiscuous males, and some are promiscuous females. For those that have a hard time getting around, like corals and clams, it’s free love. Look around at our own society and you’ll see the same scenarios, though not always for the same reasons.

In promiscuous relationships it is the female who raises the young with no paternal help in most cases. The bison and elk, where a male controls a harem, are male promiscuous. He will mate with as many of the females as he can. His goal is to have as many offspring as possible, while the female’s goal is ensure that her offspring have the best chance of survival. Surely the strongest and most fit of the males has the genes that offer better odds.

Sometimes it is the female who gets around. Several species of primates and birds practice this. The female hopes for better reproductive success by keeping her options open. It may also have the advantage that comes with several males all believing the offspring are theirs. Since the male’s goal is to have as many offspring as possible, the uncertainty will make sure they are looking out for any that are potentially theirs.

Everyone’s favorite relationship is monogamy. A pair mates for life and we think it’s so sweet. It’s almost like they’re married. This behavior is seen in bald eagles and gray wolves, for example. In this situation, both parents care for the young. In most cases, the pair nest together year-round. Not so for the Laysan albatross like Wisdom, who we met a few weeks ago. While she has a monogamous partner, they spend most of the year apart, coming together only for the breeding season. Once they chicks fledge the nest, they all go their separate ways. Wisdom and her mate will see each other again next year.

The messiest mating strategy is dispersal. Wind pollenating plants (think of pine trees) use this method, as do many sea creatures. Some environmental cue triggers corals, clams, and other sessile critters to release sperm and egg cells simultaneously. The sea becomes a soupy mess as the currents mix everything together. The pinnacle of group sex, critters who have never met or even seen each other become proud parents of children drifting off to parts unknown.

Every species is adapted to whatever mating and parenting style works best to ensure the next generation will survive. A general rule of thumb: fewer offspring get more intense parenting, while more offspring get little to no parental care. Either way, parents are playing the percentages to make sure they win the mating game.

 This week's information comes from Nature Education and the Washington Post.

Species of the Month

Don’t laugh at November’s Species of the Month. Although it lends its name to the fiction hometown of the Griffin family in TV’s The Family Guy, the northern quahog (pronounced co-hog) is a real animal. A species of clam, it was likely eaten at the first Thanksgiving in 1621. The Pilgrims neglected to save a menu for posterity, so we’ll never know for sure. Will your Thanksgiving meal include any seafood? 

Northern quahog (NOAA Fisheries)

Scientific name: Mercanaria mercanaria 

Kingdom: Animalia (animals) 

Class: Bivalva (bivalves) 

Order: Veneroida (saltwater and freshwater molluscs) 

Range: East coast of North America from Gulf of St. Lawrence to Gulf of Mexico 

Habitat: Estuarine intertidal mudflats 

Lifespan: 30 years or more, a separate Arctic species was found to be 507 years old 

Diet: Zooplankton and phytoplankton 

Predators: Moon snails, oyster drills, whelks, rays, skates, shorebirds, humans 

Conservation Status: No special protection. 

Northern quahog (Chesapeake Bay News)

Quahogs are commercially harvested. In addition to a food source, they act as a natural filter by feeding. They filter feed through a siphon that extends from the shell. Plankton and pollutants go in, clean water comes out. Quahogs are mobile, although they don’t move much. A single foot at the base of the shell holds it in place in the mud or sand and can quickly dig in to avoid predators. It can also be used to move laterally. Quahogs reproduce by releasing sperm and egg cells into the water, where they randomly meet and fertilize. Within two weeks, the quahog larvae have formed a foot and shell and anchored to the substrate. Ocean currents aid in fertilizing the eggs and dispersing the larvae. This week's information comes from University of Michigan's Animal Diversity Web.