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!

Species of the Month

Shark Week is nigh upon us and we're getting in on it with July's Species of the Month. I've chosen the most famous (or infamous) sea creature, the great white shark. While they've been known to attack people, we are not their prey. Shark attacks may be curiosity or just a case of mistaken identity. Unlike Jaws, these apex predators won't eat you, even if they do happen to bite. Sink your teeth into this quick profile!

Scientific name: Carcharodon carcharias

Great white shark (NOAA)

Kingdom: Animalia (animals)

Class: Chondrichthyes (rays and sharks)
Order: Lamniformes (mackerel sharks) 

Range: Coastal ocean areas of Asia, Australia, Oceana, North and South America, Africa, and Europe

(NOAA)

Habitat: Marine
Lifespan: 30 to 40 years
Diet: Fish, seals, sea lions, sea birds, squid, sea turtles, dolphins, whale carcasses, rays
Predators: Humans, killer whales, other sharks
Conservation Status: IUCN consideres great whites to be vulnerable, protected in the US

(NOAA)

Other information: This massive apex predator can grow to lengths of 20 feet and weigh as much as 6600 pounds! It's mouth can open to over three feet wide, plenty of room for anything it wants to eat. And that mouth is packed with razor sharp teeth. Unlike humans, gifted with two sets of teeth, the great white can apparently grow an unlimited number, replacing teeth as needed. The shark's streamlined body is built for speed and power. Not much is known about their reproductive habits. Females give birth to live young, which eat unfertilized eggs and possibly even siblings in the womb. They are mostly solitary creatures, but sometimes congregate to feed, such as at a whale carcass. In situations like this, they form social hierarchies. In addition to a well-developed sense of smell, great whites can detect electrical fields. These highly developed sense allow them to detect prey by a single drop of blood in 100 liters of water, or by the beating of its heart. The great white's prefer hunting method is to strike from below. A powerful blow is enough to stun the prey, avoiding a chase or a struggle. Across the board, fish populations are declining at an alarming rate and the great white is no exception. Sport fishing, commercial fishing bycatch, and finning take a toll, and as a large species reproductive rates are generally low. As an apex predator, populations are already low to begin with. Sadly, despite its deadly reputation the great white shark has more to fear from us than we from it.
This month's information comes from the University of Michigan's Animal Diversity Web.
nm1 https://swfsc.noaa.gov/textblock.aspx?ParentMenuId=123&id=21434
nm2 https://sos.noaa.gov/datasets/marine-migration-great-white-shark-3d/
nm3 https://oceanexplorer.noaa.gov/explorations/18whitesharkcafe/welcome.html

Everglades Flora and Fauna

Last week we explored some of the different habitats in the Everglades. This week we’ll look at some the plant and animal residents, then wrap up with some of the many challenges facing the region.

So many different kinds of animals live in the Everglades. They range from tiny biting flies to giant mosquitoes that can carry you back to their dens and every size of mosquito in between. There are also birds, reptiles, amphibians, mammals, fishes, crustaceans, and arachnids. Many threatened and endangered species call this place home. Some of the highlights: Florida panther, eastern indigo snake, American crocodile, West Indian manatee, five species of sea turtle (leatherback, loggerhead, green, hawksbill, and Atlantic ridley), snail kite, wood stork, piping plover, and red cockaded woodpecker.

Florida panther (US Fish and Wildlife Service)

West Indian manatee

Other critters you can find there include alligators, black bears, deer, marsh rabbits (which is a capable swimmer, gray foxes (which can climb trees), pilot whales, dolphins, several bat species, the gulf toadfish (which is audible to humans), roseate spoonbills, flamingoes, owls, parakeets, shore birds, waterfowl, owls, and birds of prey.

Roseate spoonbill (US Fish and Wildlife Service)

American crocodile (NPS)

Marsh rabbit (North Carolina State Parks)

Plant life in the Everglades includes sawgrass, named for its serrated edges; Simpson’s applecactus, an endangered night-blooming species; wildflowers like climbing aster, coralbean, devil’s potato, and duck potato; several species of orchids that can be found in nearly all of the Everglades habitats, including treetop canopies; and a wide variety of trees. Among the many trees are three mangrove species, West Indies mahogany, live oak, slash pine, bald cypress, gumbo-limbo, buttonwood, royal palm and sabal palm.

Sawgrass (Florida Department of State)

Applecactus (USDA)

Coralbean (NPS)

West Indies mahogany (University of Florida)

Sabal palm (USDA)

Like any other natural area, there is damage caused by humans. Some is recent, but some goes back decades. As development came to Florida, much of the water was diverted by canals. Wetlands were filled in and built over. The diminished flow and water fouled with agricultural runoff and sediment has had far-reaching effects, even today. The current red tide on Florida’s Gulf Coast is likely a result.

Invasive species, especially the Burmese python and boa constrictor, are of increasing concern. These snakes eat just about any native species in the Everglades, including the alligators. With no natural predators, their populations are able to grow unchecked. Although snake hunts are held throughout the year, they are very well camouflaged and are able to escape detection. Another species of concern is the melaleuca tree, which shades out native plants. At least a tree is easier to find than a python. Lionfish are an exotic species that eats the native populations. Increasing demand for them as a food fish is having limited success in eradicating them.

In the marine habitat, propeller scars form when boaters in shallow water mow submerged vegetation or even scrape the sea floor. Scraping bottom is far worse because it kills vegetation directly. It also kicks up sediment, which shades nearby vegetation, indirectly killing more.

The amazing biodiversity of the Everglades leaves quite a lasting impression on visitors. Unfortunately the human impact leaves an even bigger mark on the landscape and wild residential population. While government agencies from the local level up to federal are spending a lot of money to restore the ecosystems, paradoxically, those same governments are allowing more destruction in other parts of the Everglades. It’s a tragic lesson in how our lifestyle choices have consequences most of us never see or think about.

This week's information, like last week, comes from the National Park Service.

The Shell Game

Ever wonder what the difference is between a turtle and a tortoise? They’re both shelled reptiles so is it all just a name? Not exactly. All tortoises are turtles, but not all turtles are tortoises.

Desert tortoise (NPS)

A tortoise is a turtle that lives exclusively on land, while most (but not all, remember there’s always an exception) turtles spend most of their time in the water. Because of the lifestyle differences, turtles have webbed feet and tortoises don’t. And of course sea turtles, who only come on land to lay eggs, have flippers instead of legs. Tortoise shells are generally taller, while turtles have a flatter, more aquadynamic shell design.

Box turtle (NPS)

Loggerhead sea turtle (USFWS)

Now that you have that down, let’s introduce the terrapin. Terrapins are mix of the landlubbing tortoise and seafaring turtle. They spend half their time on land, half in the water. They have a more streamlined shell than a tortoise, yet it’s taller and rounder than a turtle’s. 

Diamondback terrapin (USFWS)

This week's compare and contrast is from the National Marine Life Center.