Arthropoda: Insects, arachnids, crustaceans, and others. The largest and one of the most diverse phyla on Earth, Arthropods have thrived on every continent and ocean, including Antarctica. Their most defining feature is their exoskeleton, which provides both support and protection - Arthropods have developed a number of adaptations to overcome the drawbacks of, as my invertebrate zoology professor liked to say, “living in a vacuum-sealed medieval suit of armor”. They possess body segments that have been specialized for their lifestyles, on land or sea. They have relatively complex brains, and many species have shown remarkable cognition. We have had a complicated relationship with Arthropods since the dawn of humanity; they have been critical food sources, disease-carriers and parasites, essential farming partners, and maligned farming pests for thousands of years.
Onychophora: Velvet Worms. This is the only phylum containing exclusively terrestrial members, although their ancestors can be traced back to the Cambrian shallow oceans. Onychophorans are ambush predators, moving with slow smooth steps to creep up on their prey. They have unique mucus glands on either side of their face which can spray jets of sticky slime, which effectively immobilizes their prey. Onychophorans have relatively complex brains, and some even live in social “packs” that live and hunt together. Many species in this phylum are ecologically vulnerable, threatened, or endangered.
I love insects where the juveniles eat meat and the adults drink nectar. Wasps with huge wicked sharp jaws and venomous stingers all to carry some spider back to its nest for its big soft wriggly babies to eat. She's going to go lazily drink nectar while they really go to town on it. So many fly larvae are voracious carnivores to be feared and avoided and then they turn into dopey flies that wander from flower to flower only stopping to lay eggs conspicuously close to a bunch of caterpillar eggs.
Day 1: Anomalocaris
Considered by most to be the first apex predator to ever exist, they used their arms to search the sea floor for any soft bodied critters to eat!
The other adorable millies who arrived last week: Spirostreptida sp. ‘Gorontalo’. A little larger than the Centrobolus, but still one of the mid-sized species.
Arthropoda: Insects, arachnids, crustaceans, and others. The largest and one of the most diverse phyla on Earth, Arthropods have thrived on every continent and ocean, including Antarctica. Their most defining feature is their exoskeleton, which provides both support and protection - Arthropods have developed a number of adaptations to overcome the drawbacks of, as my invertebrate zoology professor liked to say, "living in a vacuum-sealed medieval suit of armor". They possess body segments that have been specialized for their lifestyles, on land or sea. They have relatively complex brains, and many species have shown remarkable cognition. We have had a complicated relationship with Arthropods since the dawn of humanity; they have been critical food sources, disease-carriers and parasites, essential farming partners, and maligned farming pests for thousands of years.
Brachiopoda: Lamp Shells. Although these shelled animals may look similar to bivalve Molluscs, they are a completely separate phylum. Ancient relics of the Cambrian explosion, these living fossils are identified by their "lophophores", which are spiraling structures with tentacles used to filter feed small plankton and detritus from the waters where they live. These lophophores are similar to those found in Phoronida and Bryozoa, as these phyla are closely related. An anchoring appendage called a "peduncle" keeps them firmly rooted in the sediment, which makes them difficult for predators to dig up. In the Paleozoic, these animals were some of the most prominent reef-builders on Earth, producing impressive structures analogous to modern oyster reefs today.
In the Cambrian seas, strange, many-legged creatures were swimming and crawling. With signs of a segmented cuticle and of branched gills raised atop their legs, Opabinia and Anomalocaris were close relatives of true arthropods. The latter would develop this further into a fully articulated exoskeleton, with trilobites emerging during this same period.
Crustaceans are the first large group of arthropods, mainly occupying aquatic niches - from tiny one-eyed copepods to decapods like crabs or lobsters. Not all aquatic arthropods are crustaceans, with sea spiders and horseshoe crabs being more closely related to arachnids.
Arthropods radiated four times on land. Arachnids (spiders, scorpions and relatives) developed book lungs - tightly folded sheets maximizing surface area for respiration -, and fused the head and thorax in one structure. Myriapods followed the opposite path, elongating in tens of repeated articulated segments. Then two groups of highly derived crustaceans: isopods, and, the most successful of all, hexapods (insects, springtails and relatives). Both isopods and springtails are today ubiquitous in soils, playing essential roles as decomposers.
The hexapod radiation on land was followed by one in the skies. The only non-chordates to have achieved flight, insects quickly dispersed and diversified in hundreds of niches, dominating the skies for a full hundred million years. Even today, their success is hard to understate: half of the two million described animal species are insects, with possibly ten million more awaiting to be found.
Some arthropods depart radically from the usual, segmented and armored body plan. Tongue worms, enigmatic parasites bearing five hooks around their head, were only recently recognized to be highly derived crustaceans. In the same way, parasitic barnacles like Dendrogaster or rhizostomids have lost virtually all arthropod characteristics, reshaping their anatomy to fit their new role.