Just back from Norfolk where I gave talks at ODU & NBG. The 1st on Anacardiaceae, 2nd on PNG. Pistacia chinensis is planted all over town!

Nothing says summer like a fresh, local, tree-ripened peach. As I was eating one this morning, it broke in two along the pit, exposing the seed inside. This of course is the perfect opportunity for a botany lesson! A peach is a fruit type known botanically as a drupe. Drupes are fleshy with seeds enclosed in hard pits.

My morning snack: peach (Prunus persica, Rosaceae)

In this peach you can easily see all three layers of the fruit wall, known collectively as the pericarp, which develop from the ovary wall of the flower. The outermost layer of the pericarp is the exocarp (also called the epicarp), which you know as the soft, fuzzy skin of the peach. The delicious and very juicy layer in from the exocarp is the mesocarp. The hard, woody pit in the middle is the endocarp (often called the stone in drupes). Inside the endocarp is the seed that is white with a brown seed coat.

In this peach you can also see vascular tissue in the flesh and seed coat (look for the horizontal lines in both) and sap leaking from the broken pit (shiny golden droplets at the right top and bottom of the seed).

We saw a lot of animals on our Costa Rica trip that were interesting, but did not make it into the blog yet. Here are some pictures with ID’s where we have them. If you know any of these species, please add identifications by posting a comment and I’ll update the post with the new ID and credit to you.

Hermit crab on the beach.

These little hermit crabs were everywhere! Hermit crabs use the discarded shells of other animals and have to change their shell as they grow. If you search really hard, you can find naked hermits upgrading their shells on the beach. They are in the animal kingdom’s superfamily Paguroidea, but we do not know what family or genus. UPDATE: Marie has identified this little creature as Coenobita compressus in the family Coenobitidae via a comment posted on the blog.

"Lefty" crab (Uca sp.) in the mangrove mud.

We affectionately called these little crabs “lefty” because most of the ones we first saw had their pincher arm on the left (although upon further inspection of the population, many were “righties”). Thanks to a comment from Ana, we now know that they are a species in the genus Uca.

Land crab just outside the research station.

Pacific land crabs (Cardisoma armatum), also known as rainbow crabs and parrot crabs, come to the Pacific shore to reproduce before returning to their primary homes in the forest. They are very brightly colored in their youth, but fade as they age.

Sand dollar on a piece of beach driftwood.

We need even more help with the identity of this little creature. It is a sand dollar that washed up on the shore of Playa Grande and all we know is that it is in the order Clypeasteroida.

Sea snail from the surf sand in Keren's hand.

Sea snails are gastropods that live in saltwater. We saw a few different sea snails in Costa Rica. This one was scooting along just under the sand as the surf was coming in at Playa Grande. We have no idea what species it is, so please help us out.

Butterfly in the forest of Cerro Morro.

We saw many butterflies, but I was only able to photograph a few of them. A beach butterfly appeared earlier in a post by Ely. This one was about halfway up Cerro Morro flying low in the forest and is another species we have yet to identify.

Heron fishing in the mangrove.

This beautiful heron (Ardea species, family Ardeidae) was a common sight during our fieldwork. We greatly enjoyed watching this majestic bird fish and fly.

Male howler monkey making his way through the canopy.

The final animal of this post is one that we heard often and saw a couple of times, the mantled howler (Alouatta palliata, family Alouattinae). These monkeys are found throughout Costa Rica and the males make a sound somewhere between a barking dog and a mad pig to alert others of their presence. It works. You can hear them many kilometers away. This is a monkey you don’t want to aggravate – if you do, they will pee or poo on you! However, howlers are rarely disturbed by people and for the most part tend to ignore them.

We got back at 3AM. We’ll have a few more CR posts over the next couple of days to share some more pictures and adventures with you.

Acacias are some of the most ubiquitous trees in the Neotropical dry forest. We have collected several acacia species at Las Baulas National Park, some of which exhibit remarkable plant-ant interactions. The trees provide the ants with room and board and the ants provide protection for the plant.

Acacia trees: A) yellow Beltian bodies on young leaflet tips; B) inflorescence; C) extrafloral nectaries on petiole, swollen thorn, and ant; D) swollen thorn and ant.

Ant acacias have swollen, hollow thorns in which the ants live. The queen drills a hole in the thorn to gain access. The acacia also provides the ants with two types of food: sugary nectar from extrafloral nectarines at the base of petiole and protein in the form of Beltian bodies that are produced at the tips of new leaflets. In exchange, the ants protect the tree from herbivores by attacking any animal that comes in contact with the plant. They also attack other plants that touch or grow too near their acacia. They trim encroaching branches from neighboring trees and shrubs and cut down any herbaceous plants or seedlings that grow under the acacia. This is one of the most intricate and well-studied mutualistic relationships in nature.